more HP!!!

it seems like i have got most of the basic mods so for and i'm looking to go for some mods like heads RR's or a throtle body but i have no clue on what ones to put in and how much HP it is going to give? can you guys try and help me out with some of these Q's please

1. what kind of heads? how much $, HP, and labor?

2. roller rockers is 1.6 good and are they easy to install. (my dad is a good mechanic) so if it wont take to much time then my dad will go for that.

3. may be a Throtle body but what size and kind?

Thanks for any help,
Dave