If you really want to stay at a low level you need to avoid playing every day, the 880 bonus you get once you get to 8 consecutive days will get you up the levels quickly when you're fairly new. CTTH gives little exp so will slow you down but also won't help you learn course management. Why do you want to stay a low level? You won't get access to the better clubs if you do. I can see why someone would want to stay in a low tier but I'm not sure there's any benefit from being in a lower level than someone else.
With avatars it's the other way round. Female avatars have, or used to anyway, more movements in the swing so players who judge power from avatar movements could do so more precisely with a female avatar. I say used to because all avatars had the number of movements reduced a while ago to reduce load times so it may be that they're the same now.
As for irons, generally the higher the level required to get them and the more they cost is a good indicator of how good they are. The downside to your first set of decent clubs is the meter speed, this will be quite a bit faster than you're used to. I assume the 1250 set is the Burner 2? They have a slower meter but it will still be faster than you're used to. If you can wait a little longer and have the credits the R11 at level 32 will keep you happy for a long time once you get used to the meter. It's very easy to buy several sets of irons as you progress which is a waste of credits really, at least the R11 could stay in your bag a while.
You'lll also need a driver and wedges at some point. It's never ending really, always something else on the wish list.
Have fun.