Practice barre chords higher up the fret to help you get the right tension (easier to place the fingers up the fret!). Play the f-shape on the fifth fret and go up a fret at a time to say the 10th fret and go back down to fifth. After a while go down from the fifth to the 4th fret etcetera. Think about the thumb with barre chords: it always wants to come towards you, restricting the reach of the fingers. thumb usually in the middle of the neck, nice and firm.
Strings can last anything up to 6 months if you keep your guitar in a case between plays, don't play with dirty hands and wipe the strings after each session. I usually wash my hands before playing and never, ever eat while playing!
Masterblaster: you got it. Couple of minutes work-out with the fingers, couple of minutes investigative research and problem solving and all the rest is fun playing! Do that evry time you pick up the guitar and you will be a good gutarist with a firm foundation in a lot less time than many who either A) only practice practice practice without enjoying themsleves or B) only muck about without improving!