Introduction and sew in question

I can't help you with the sew in question, as I've never tried extensions, but there's an extension forum here you might try for that.  The people there would know better than me, but I heard extensions can cause breakage, so if your goal is long hair, you may just want to wait it out to grow your own (unless of course they tell you there are new kinds that don't pull your hair out, then, hey go for it!). 

For your breakage, try to figure out why it breaks at the front, if you can figure it out, then you'll know what to stop doing.  It might be you are pulling it too tight into barettes or a ponytail, causing the front hairline to pull thin, or it might be getting caught in the hinge of your glasses/ sunglasses (if you pull one hair out every time you take off your sunglasses, that adds up after awhile).

There are really no products that are going to make it grow faster, but if you put conditioning products in it, or use oil as your leave in (like jojoba or coconut oil), that will help it grow by preventing so many tangles, so you won't need to trim as much off as you'll have less splits and breaks.

Silicone products can build up and cause breakage after several months, so if you use them (silicones are in most conditioners these days and many shampoos), be sure to use a clarifying shampoo once every 2 months or so to make sure they don't build up, then you won't need trims for this type of breakage either.