I think most chess games and engines support the import and export of PGNs. I use Chess Tiger and Stockfish for my iPhone/iPad and both support PGNs. I also downloaded Stockfish chess engine 2.3.3 on my Mac OS. I can import and export between all three. I use Stockfish on my Mac to store games I've played and save them with names based upon dates and opponents. This allows me to refer back to them after later. I am sure others may have a better way to do this but this is how I deal with game I study.
In terms of tactical visualization, I use a checklist of things to investigate. I look for pieces that are already attacked as well as potential issues such as possible checks, pins, forks and a few other things. I do this for my pieces as well as for my opponent's side. For each, I check to make sure there is enough protection. If there isn't then it becomes a candidate move to fix if it is my own issue or attack if it is my opponent's issue. Again, I am sure others may have a better way but this is what works for me. Good luck.
I have just got my first "serious" chess book. I have a study plan and my first book is "Back to basics: tactics" by Dan Heisman. I have a hard time visualizing all the moves for some problems in my head and think i would benifit more from the studys if i was able to insert the positions into a chessprogram and save the positions so i could re-do the puzzles and positions ony my computer. My question is how would i get the most out of studying my tactics, how have you done it?
Bonus: How could i maybe go about to create my own PGN's and what program would be the most user friendly to create a cataloge of the different chapters of my book?