You can do a hundred transfers between now and Friday, but after that, you accrue one transfer "credit" after each weekend, but you can never accrue more than two transfer "credits". So after the first two weeks, you can transfer two players out and two in. Or, if you want to use your first transfer after week 1, you can too. Using two gives you more flexibility with your money.
Twice a year you are awarded a "wild card", which you can use to do a mass clear out if you want, unlimited transfers.
As the season goes on, players lose or gain value depending on their performance. So right now, RVP is something like 13m, but if he sucks for the first month, his price will drop.
You'll want to choose players that you think will start and play most of the game, week in, week out.
Whoever you make your captain will score double his points each week, so choose that one wisely.