Chess software help

After years of using Fritz 5.32, i have decided to upgrade.  Now my question is this...I have always enjoyed using Fritz, and im not concerned about the chess engine i use being the highest rated.  Afterall Im a USCF B player, i cant see shelling out hundreds of dollars for something rated 3008 as opposed to something rated 2980.  Factors to consider.  Im 48 and study, but i dont put in 8+ hours a day.  My goal is to reach USCF A player by the end of this year.

1.  What chess engine should i use?  Id like to stay with Fritz, and get the software that goes with it on chessbase.com

2.  Is the full paid version of chessbase worth paying for, as opposed to the free version, and or SCID, and ChessDB?

Any and all suggestions will be appreciated.

After analyzing my games, i run them through Fritz.  And now i want to start purchasing the software that runs with Fritz. 

Which engine should you use?

Houdini (version 1.5a) or Stockfish or Komodo or Critter are all fine.  All are stronger than any version of Fritz you will find, including Deep Fritz and all are free.  You can use all of these engines, and many others, WITH the Fritz interface if you so choose. 

I myself happen to be a fan of WinBoard.  That's the GUI I find myself using most often.  I use this to analyze my own games, have engine vs engine matches, play over games of GMs, etc.

Is the full paid version of chessbase worth paying for...

With so many free chess interfaces to choose from, you certainly do not have to pay for Chessbase at all if you don't want to.  Purchasing and using Chessbase won't necessarily help you to achieve your goal.  I'd certainly first download and try SCID and the ChessBase Light and all of these other free chess software and tools.

There's almost no reason to pay for a chess engine, as the best ones are free. Stockfish, houdini, fire, critter, komodo are all better than almost all commercial ones.

About paying for chessbase, if you don't need very advanced database functions; ChessDB, SCID and the like are surely good enough.