I have some rebuy strategy questions:

Tonight I played a live rebuy tournament. This is the structure:
Starting stack is 700 chips and that costs £10. You can rebuy when you're on 350 chips or less. The blinds are 25/50 for the first 45 minutes. Then after 45 minutes the blinds go up to 50/100 for another 45 minutes. After 1hr 30 mins, the rebuy ends and you can buy an addon of 1000 chips for £10.
There are between 30 and 50 people at the start and the top 5-8 players get paid.
The tables are not shorthanded. (about 8-10 people per table).

At the start of the rebuy, everybody is very aggressive and people are going allin every other hand and then rebuying again and again and again. Towards the end of the rebuy period, people become less and less aggresive as they accumulate more chips and once the rebuy period ends, the play becomes much, much tighter and turns into a usual freezeout tournament.

What strategy should I use to play in this tournament? I don't play a lot of rebuy, but I read the post on this site about playing in rebuys and I realized you do have to be very aggresive at the start and plan on buying in between 3-10 times.

So far, I've been to this tourney 4 times. The first time I played it tight in the rebuy period and got to about 6000 chips before loosing, having only bought in twice with no addon. The second time I went, I bought in £20 again and played it tight as well and didn't get anywhere at all. Got knocked out the first hand of the freezeout and I didn't stand a chance of doing well.
The next time I went, I played slightly more loosely and did very well. (I was going into hands with A9o and flopping trip nines - the other guy flopped trip nine with a 4 kicker. Another hand I went in with QJo and hit the Q which was top pair, I quadrupled my money beating hands like QT and 2nd top pair, etc). I bought in once and by the end of the rebuy period I was one of the chip leaders with over 10,000 chips. I bought the addon and finished 7th at the end. I took home £40, which was a bit disappointing because I had started off so strongly. The reason I lost though was not because I played bad poker but because I got unlucky hand after hand. Eg. Putting people allin preflop where I was a 70+% favourite and loosing everytime. I didn't loose a lot of chips in these hands but had I won them rather than lost them, then I would have been chip leader by the time I got to the final table rather than being quite short stacked with very big blinds.
Tonight I played again, I was much, much looser and was going allin preflop with a lot of hands. I ended up buying in 4 times and spending £40 and leaving a few minutes before the freezeout. I didn't win one hand all evening (except for one split pot) and that was mostly because of bad cards and when I did have good, I was always up against someone with bigger hands.

How am I supposed to do well in these tournaments? They're very expensive for me and my very small bankroll. I play online a lot and I would never dream of playing for such big stakes. I play $11 SnG and $25NL cash game. This rebuy tournament costs me $20 per rebuy and I can expect to be paying $100+ everytime I play. Should I just giveup on this rebuy tourney till I have a proper bankroll?

If I can get to the end of the rebuy period with about 5000 chips (including addon) I should be in good shape to finish ITM. Can anyone help me out here?

The problem is, I start off with an M of less than 7 and there's not much chance of stealing blinds like I might do in an SnG. Also, if I rebuy after 45 minutes. I start with an M of less than 4. Any help? Should I stop rebuying after 45 minutes and leave if I loose?

BTW - I mentioned above that I was going in with hands like A9o and QJo. I don't usually play hands this weak. I was only playing them because it's a rebuy.