I am considering purchasing train tickets online through a company called "RailEurope" before traveling to Italy/Switzerland in 2 weeks.

1. Would it be a good idea to do this, or should I wait until arriving? Will it most likely be cheaper if I purchase once I arrive in these countries?

2. Are ticket lines usually long at European train stations? If so, I'm assuming it would be better to purchase in advance...

3. Does the Swiss rail company "SBB" connect to Milano Centrale? I could not find this info on their website. I am assuming I will be using Trenitalia throughout Italy and will have to connect to SBB somewhere along the line...?

Trenitalia is the Italian rail company so yes, in Italy, that's what you will be using.

#1. You can buy Swiss passes in Switzerland, but most other rail passes require purchase before departure. It's likely to be cheaper to buy point-to-point tickets for Italy unless you are traveling long distances daily.
http://www.swisstravelsystem.ch/en/

#2. Most of the larger train stations have rows of ticket machines (in Italy, they are touchscreen in English) so there is no need to stand in lines. Typically, you can get big discounts for buyin in advance online directly from each countries rail company (not RailEurope or other resellers). Trenitalia has mini fares which can reduce tickets as much as 60%.
http://www.trenitalia.com/cms/v/inde...003f16f90aRCRD

#3. I'm not sure why are aren't finding this. Just enter your start city (Zurich? Geneva? and Milan. There are also Smart Fares (19€) between Milan and certain cities in Switzerland.
http://www.trenitalia.com/cms/v/inde...003f16f90aRCRD

IF you are traveling from Milan to Switzerland, you can purchase on Trenitalia (they require pick up in Italy). If you are traveling in the opposite direction, you will need to purchase on the sbb.ch website (called saver tickets,supersaver, special discount or Go fare). This fare is not always available and sometimes doesn't show up until you select trains/dates, etc.

You can book train tickets from Zurich, Basel, Geneva to Milan at www.sbb.ch from 34 CHF, about $37, IF you book well in advance, max 90 days. You cannot get these cheap fares at Rail Europe, nor can you buy them close to departure.

Then use www.trenitalia.com foir Italy. Choose between a Base fare which you can also buy at the station on the day to stay flexible, or a cheap 'Mini' fares which will save money if you commit to a specific train, limited changes and refunds. Booking opens 90 days ahead.

Tickets to Switzerland starting in Italy can also be booked at www.trenitalia.com, in this case look for the drop down box marked 'More fares' AFTER you've selected a train with full-price fares shown, and look for 'Smart Price'. From 19 euros. It won't book to all Swiss cities, sometimes you have to break up the journey, eg it won't book Milan to Zermatt, so book Milan to Visp and buy a separate Visp-Zermatt ticket when you get to Visp.

Thanks! I've already purchased several of my tickets online using Smart Fares. However, of one of my Trenitalia trips (Arth-Goldau to Milano Centrale) I could not print out the tickets. Apparently I have to do this at select stations in Italy...? Does anyone know the proper procedure for doing so? I just

Surely Arth-Goldau is in Switzerland, not Italy? So use the sbb.ch Swiss railways site to book it.

In my last paragraph above, I pointed out (as did maninseat61)if your travel starts in Italy, you purchase from Trenitalia. If it starts in Switzerland, you purchase on the Swiss site.

If you've already purchased the Arth-Goldau ticket from Trenitalia instead of the Swiss site, I hope you are traveling in Italy first so you can print that ticket at a station. Here's a list of the self-service stations.
http://www.trenitalia.com/cms/v/inde...0a3e90aRCRD#26

If you are traveling in Switzerland first, you will have to buy the Arth-Goldau to Milan from sbb.ch.

I am flying into Milan then going to Switzerland, so I will pick up the tickets at Milano Centrale before I begin. Are there self-service machines that I should loof for at the station? Do I just type in my PNR code from the ticket?

See the info already posted above about self service machines.

In the large stations, there are rows of ticket machines (look similar to an ATM machine). They are touch screen with English option. Scroll down until you see the picture of the self-service machines on this link (the pics are from Termini in Rome).
http://www.roninrome.com/%20transpor...ickets-updated

Scroll a couple of more pics and you will see a screen shot of the machines selections - buy your ticket, collect your ticket (what you will want to click), etc.

. You can buy Swiss passes in Switzerland, but most other rail passes require purchase before departure>

But when I checked on prices for the exact same Swiss Pass here or there last week they seemed to be significantly cheaper if bought in the U.S. - anyway you can check prices in Swiss francs at www.sbb.ch (Swiss federal railways who sells passes at any Swiss station) and thru any U.S. agent like www.budgeteuropetravel or www.ricksteves.com - www.raileurope.com actually is the wholesaler of Swiss Passes in the U.S. but IME the other two agents give much better service and prices are universal.

If you are traveling with kids under 16 on a Swiss Pass there is a current special deal giving families 50% off Swiss Passes - unfortunately you must be traveling with kids of your own under 16 to qualify.

I have decided not to purchase rail passes because after much calculation, point-to-point will be almost $200 cheaper. We are not traveling too far, just between Milan and Lauterbrunnen.

Within the Berner Oberland you may still want to investigate the Jungfraubahn Pass good on all trains in the area, including the really pricey one to the Jungfraujoch and also to Schilthorn - I figured once that if I took just these two trains that pass would pay off and of course you could use to get to Lauterbrunnen, Murren and all around - may cover lifts as well.