This hobby is known for rewarding those who "jump into the deep end" by "drowning" them.

You said it yourself: a Sukhoi is not a good second plane. It is too advanced for a beginner's 2nd plane for more reasons that just its flying characteristics. As you have found out yourself, the instructions are not as in-depth and laid out as beginner's/training planes. Your Sukhoi is not designed for someone new to the hobby; it demands a level of skill that only comes with experience. In your case, it doesnt state how to mount the engine or the center, but it leaves it to the builder, which the instructions assume has had previous experience with. In other words, you have to collect skills as you progress in the hobby. You can simply get a "hot-stuff" plane and ask for help from people online. You need to learn either from experience with planes that are designed to teach a beginner, or learn from someone in person who is more experienced that you, i.e. your instructor. You need to build your way up to these planes! You cant just take a big leap and expect everything to go smoothly.

Let's not even go into how its not a good 2nd plane flying-wise....

Please, for your own sake, your money's sake, a most importantly the planes sake, put it away for now. You need more experience. And the truth of the matter is that, no matter how many times you tell yourself you'll be responsible and not fly it when its finished and that you'll wait until you have more flying time, the temptation of flying a ready-to-fly plane is too great, and you'll undoubtately fly it before your flying skills are up to par. Leave it unfinished, and get a 2nd and 3rd plane, like a Sig 4-Star or Sig Somethin' Extra. You'll have a better chance of succeeding in the end, and less likelihood of messing up.