1) Yes you can choose to train against specific openings.
2) Opening preparation should not be the focus of your studies at this level. But playing against the engine will give you a wider exposure to your preferred openings as a whole.
3) Learn the ideas in the positions. Just memorizing moves is fruitless (as you are finding out).
Build yourself a small opening book, containing just the lines you want to play. When you set up your match versus the computer, make sure it's this book which is active, then the computer will only play into those lines.
Alternatively, any existing book you have stored in your HDD, add weights to the lines you want to play, the computer will then select these openings from the larger book. This is a less practical method though, those weights can be reset later, but IMHO it's much easier to use a separate book.
I am new club player who is lost against a lot of different opening that I face in tournaments. Would chessbase in combination with fritz 16 help me train against different opening? My daily chess rating in chess.com is around 1500 but blitz is around 1100. In OTB, in the club and in tournaments that I play, I don't have a rating because it's still provisional. I can compete with players who are close to 1500 but because most tournaments are "open" tournaments, I get paired against much higher rated players and find it hard to not be at a disadvantage within 15-18 moves and usually by move 30-40 I have to resign or lose. If anyone knows if chessbase or fritz is right for me please let me know.
I do a lot of tactics training and end game training but I don't get to situations where I can use that aspect of my preparation. I mostly stick to playing 1. d4 and with black pieces I only play Sicilian. In chess.com at my rating almost everyone plays the Bowdler attack against c5. I found playing the Schevenigen variations gives satisfactory results but it also limits my preparation for tournament play because no one plays the bowdler attack in tournaments. I don't know how to play against 1. Nf3 or even C4 openings with the black pieces. I learn by doing so just reading about opening wouldn't do it for me. I would have to try the moves out over the board or on a computer software multiple times to commit the lines to memory. I need to perhaps develop a repertoire but don't know how to start. I am sure I can do a lot more training in calculation, tactics, strategies, etc will help me improve and I plan on continue to train in those areas too but it's frustrating to be worse after 10-15 moves. Any suggestions?