i5 vs i7 in laptop

Hi,

New to site.
I did a search for "i5 vs i7", "i5 i7" and nothing popped up.

So my question is: for a desktop-replacement lappy, which core would run cooler? An i5-460 or i7-740?

Also, I heard of a term "hyper-threading".
Did a search and some sites say i5's don't have HT, some say they do.
Did a search for "i5-460 hyperthreading", still found conflicting info (yay go internet!).

Lastly, in your opinion, is the i7 core worth the extra expense for: light gaming and normal stuff we 20+ year olds do.

Thanks for any info!