What are my chances of getting them for a Monday night performance? Should I just buy the $55 tickets that are already discounted?

We could do the Sunday night, too. Also, is there a good chance I can buy the tickets with the hotshowsclub.com discount code at the theater if I don't get the tickets in the lottery?

Monday is the slowest night on Broadway, so your chances are probably fairly good. However, my understanding is that the $20 seats are way up front and the miking is very loud in that area. You might be better off getting other discount seats, perhaps half-price at the TKTS booth in Times Square.
Forget Sunday night, Monique, as the show doesn't perform that day.

We saw Rent a week ago, and the miking is loud all over.... .

I would give it a try for the $20 tickets, if I were to go again.

www.siteforrent.com says:

Daily drawings will be held at 6:00 PM for 8:00 PM shows, 12:00 noon for the matinees and at 5:30 PM for the Sunday evening performance.

But now that I look at it, ticketmaster doesn't list a Sunday show. So Monday it is. Glad to hear that's the slowest night! Thanks!