If you currently weigh 205lbs you might want to consider cutting down to around the 185lb weight classes. Most amateur promotions go by the USKBA's weight classes which would put you around Super Light Heavyweight (175-182.9), Cruiserweight (183-189.9) or Super Cruiserweight (190-194.9). If you are thin though and you want to go in the opposite route you are going to want to put on muscle to bring your bodyweight up to atleast 215-220 to fight at Heavyweight (195-209.9). However if you are worried about the weight cut then i'd look to put on even more muscle weight because Super Heavyweight goes up to 249.9 and will most likely have guys cutting down from atleast 260lbs.
Depending on the shape you are in currently, training will drop your weight anyway so if you are looking to stay up in the pounds i'd also consider lots of heavy lifting and supplementing with weight gainers for a little until your weight is up near the area you want it to be. Obviously stay away from weight gainers if you want to keep the weight down. Personally, i'd rather see you at Cruiserweight or even Super Light Heavyweight if you can make it down to 183lbs. Being that you are 6'4 you are going to be a nightmare to get inside on, chances are you'll have the reach advantage on most of those divisions. I'm glad i don't fight at those weight classes, i'd hate to have to try to get around your reach.
Time frame to get ready for a fight really depends upon the individual. If you have a previous background in martial arts or wrestling prior to training MMA you might be ready faster than someone that has no prior experience. But even without experience you might be what we like to call a sponge and pick up enough to fight an amateur bout in as little as 3 months. It all really depends on you and how much time you put into it. I fought my first 2 Muay Thai fights with less than 5 months experience. My first MMA bouts came about 3 and 5 months later.
For standard training, 2-3 days a week is a good idea. If you are gearing up for a fight i wouldn't suggest going less than 4 days a week. Our fight team puts in normally 5-6 days week when training for a fight unless they work out a schedule with the instructors to allow them to get away with 4 days. And a normal training camp for a fight is 8 weeks. Sometimes they are 10 or 12 and sometimes less depending upon how far out from the fight it gets booked and what the situation is. If you are fighting for a title (amateur or not) you should be doing atleast a 10 week camp. But it's always suggested if you are a competing fighter to stay in shape, you never know when those short notice fights will pop up. I fought a Muay Thai bout on 6 hours notice once because a fighter didn't even show up for weighin's. I was there with my gear and said "fuck it". I lost the fight convincingly but it was good experience in what not to do.
Lastly, i would suggest looking into a different school than TSK. They make great advertisements and have a few decent instructors but they just really made the transition from a Karate school to a MMA school. TSK as a Karate school was just barely more than a McDojo as well. I'm not a fan of them but if they are the only school in your area then you really don't have an option. But if they aren't the only school, try to find one with a history as a MMA or even a Muay Thai or BJJ school. Normally they have a way better foundation underneath them. Do research on the intructors as well.