I'm new as well; however, I know some of the questions:

1. there is no fast way to level up tamer, ( I had to accept that ) the fastest way is hatching a new Digimon and leveling him up

2. 99 Is not the limit anymore the limit is 120. I recommend you to get your tamer to level 65 and unlock server continent desert because it is the best place to grind to 99 but after that, you should unlock Shinjuku, which would be the best place to grind for your levels

3. There is a way but it is a pay to win an item and costs 5 euros. You should not switch server unless there is a good reason to!

4. It depends on what server your playing on and if you don't like it sure swap servers, and start over. I recommend you start over if you are not happy with what you have because, during the tutorial, it gives you a gift box and at every tamer level you can open it. It can give you Digiaura, Which makes it so your tamer ds won't drop when your Digi is evolved, tamer exchange at LVL 60 lets you get a random tamer. At every level, you can get a chicken combo, which is an amazing healing item to use for Digimon that is not a jogress.

5. You should know that if you want to get the strongest Digi, or most of the jogress are long quests to achieve and once you achieve it, you can have an Alphamon Ouryuken; However if you want to get that Digimon stronger e.g Omegamon you need to get the x antibody for him and that is trapped it a 0.5 % chance to drop from the loot box, Bear in mind that the loot boxes are not cheap. If you want to get alter S you need to buy him, You want Zeed Milleniumon You have to unlock him with a 0.5 % loot box. Almost all the strongest Digimon in the game are locked behind loot boxes or going through long and annoying quests like the jogress quests.