>is it adviseable to buy tickest online now?

Yes, buy the ticket from FRA to Paris via Mannheim and specify a break in Mannheim. This way you may be able to get cheaper tickets to Paris. Within Germany it mostly matter when you buy the tickets, but in France the tickets get cheaper if you buy them earlier.

Your ticket will be a printable PDF file. Don´t forget to bring exactly the same credit card you have paid with.

>As i will reach FRA at 9pm at night, will ticket booths still be open?

The booths maybe not, but the ticket machines work 24/7

>or any chance that tickets will be sold out?

To Paris? It may be (technically) although very imprbable for that early-morning train. For trips within Germany (e.g. to Mannheim) tickets cannot sell out.

thanks to dalai and alta again for the inputs, one last question, the DeBhan from Mannheim to Paris, stops at which station in paris? can't seem to figure out 'Paris Est' is it Gare Du I'est ?

thanks in advance

>DeBhan from Mannheim to Paris, stops at which station in paris?

The trains end in Paris Est

Est = East
Gare = Station

>can't seem to figure out 'Paris Est' is it Gare Du I'est ?

Yes...

great! thanks again a million vry1 who contributed, esp to Alta and Dalai!

Happy holidays