Yes, add the whole bottle. The "up to 30 gallons" part just means that the amount of bacteria in the whole bottle is good for any size tank up to 30 gallons. (Not sure if that made sense...it did in my head lol).
If the bottle says add the fish immediately, add the fish immediately. Like I said, I've never used TSS, I've just read reviews and such from other people who have.
As far as acclimating the fish, don't just dump them in the tank. Float the bags for about 15-20 minutes to allow the temperature to adjust. Then open the bags and pour a cup of tank water into each bag and reclose them. Repeat this every half hour or so for about an hour and a half. Ever since I started acclimating my fish this way, I haven't lost one. What this method does is help the fish adjust gradually to the new conditions of the water they'll be living in. Also, add the pleco first, then about 15 minutes later add the oscar.