OMG, Mike made a topic!!!!
Great idea, btw:
1. Is 435 Congressmen enough to provide adequate representation?Given how large our country is (300 million, wow!), I would say no. If my math is correct, our current headcount means that we have one representative for every 690,000 people. That seems way too large for it to truly be representative.
2. If the number of Congressmen should be changed: When should it be done? How do we determine what changes to make?After the Democrats get in power

KIDDING! As for when, I'd say after the 2010 census. This is for two reasons. First, it gives us an adequate window of planning to account for the new Congresspeople. Second, hopefully it depoliticizes this a little as no one can say with any certainty what party would be in power at that point.
As for what changes, I think we should shoot for a bright line of representation. Perhaps we should start by at least reducing the representative proportion to 1 for every 300,000 people. Of course, that would bump the number of reps to at least 1000. Perhaps that's too aggressive, I think that number is certainly worthy of debate.
There is unquestionably a risk in doing this. First, it has the potential to make a bloated government even more so. Second, it can make the levels of corruption in Washington D.C. possibly even more rancid. It could also help with it. Because of that risk, I would include term limits in the reapportionment. Unfortunately, I also know that divorces this legislation from ever passing, but it would definitely help.
3. If the number of Congressmen should be changed significantly: What is the best method to initiate this change?Well, can we trust Congress to properly amend the 1929 act? Probably not. So I guess the states would have to call a Constitutional Convention. Either avenue is pretty tricky.