You should read the game manual and the introduction threads in this forum, they have a lot of information ;)
As for your questions, the TV contract is the same for all teams in your league and will stay fixed for the entire season. It's roughly dependent on the overall talent in your league, but across the board the TV contracts in all div. III leagues should be fairly similar.
Each player's salary is determined by his skills. Depending on each position, different skills contribute differently for the total salary. At the start of each season the salaries are updated, so players that received training and improved will have bigger salaries, and players who didn't improve or even dropped in skill (happens for players older than 32) will have smaller salaries.
Hope this clarifies your questions, and good luck!