If he can honestly give YOU what YOU want from a relationship then try again but make sure you both clear all the issues between you and deal with or cope with the baggage. However, do not go back if he cannot give you his absolute commitment. Life is too, too short to waste your time in a relationship which is not, mutually, great. If a relationship is just a 'make do' one, then its not worth sticking with - trust me!! I believe it is better to be on your own than with the wrong one, only you know the best course of action.
It sounds like you already have doubts about this relationship before it's even started again! I think the best thing would be to actually sit down and talk about it. This would give you the opportunity to talk about your need for commitment etc and I should think he's got some things to say himself. Try to ditch the texting for now as it doesn't seem to be getting you anywhere. If after speaking to him directly you are still unsure just let him know that you need time to think about things. If he genuinely loves you, he will be able to give you this time and it will also help show you if he can commit.
Isn't THAT the million dollar question? Could be any number of reasons: a need for him to still be "in control" of the situation, he's lonely, he has issues with separation, change, etc.
Bottom line is, if you haven't told him how much this bothers you, do it NOW. And don't answer his text messages; just use that very handy Erase feature.
I would not bother with this guy. Apparently something happened the first time that made it not work, and most likely it's not going to work the second time. Ask him to leave you alone and if he doesn't, go to the mobile store and change your number.
Like above says, change your number. Ignore him (easier said than done I know) but if you rise to his pathetic attempt of having a trip down memory lane. It just makes it harder for you, and prolonging the closure. Text back a few of the bad times and say, this is exactly why I DONT want to get back with you, and the good times will not erase these bad times. Please leave me alone, if he still pesters you, mobiles these days can block numbers and texts etc. if this does not succeed, Change your number! Hes pushed you to this.