New to all of this! Help!

I have been going through this site and there is sooo much information that I thought I would just ask for advice!  I am competing in a pageant in 4 weeks and my hair is not full enough.  It always tends to be very flat on top no matter how much teasing or spraying I do!  I am considering extensions but only for the pageant.  Soo...just a few questions...

I have very naturally curly hair that I straighten with a hair dryer and professional flat iron almost everyday.  Because of this, I am worried that the extensions won't work for me.  Can they withstand the heat of my straightening? 

I am also concerned that they will not blend into my hair because of my original hair's texture.  I do not really want length, just volume. 

The other question I had was about coloring.  I have blonde hair with highlights, but I am planning on making it darker for the pageant, just a little bit.  I am concerned that the extensions will not match and be very obvious. 

I guess like everyone else I am worried about damage to my hair.  What is the best method for applying temporary extensions without risk of damage? 

I found a specialist who uses Great Lengths Extensions and Hairdreams.  Are these good products? 

Any advice would be greatly appreciated!  Thank you so much!

you could always make your own clip ins.  buy hair in the style you like (volume wave, curl, etc) that's longer than you like and bring it with you when you get your hair dyed so your stylist can dye it the exact same shade.  then clip it in, have the stylist cut it for you so it'll blend easy and just remember how and where they go.

this is just a pageant, right?  one night, in-and-out?  clip-ins or protacs will suit you just fine.  you don't even need to buy super expensive hair because you just need it to look gorgeous for 8 hours.