Interlinking for SEO

How important is interlinking in SEO?

I can two options:

1 Go with separate domains.

2 Put all squeeze pages on one domain.

My content wont be superb since they are squeeze pages (but it actually might look like legit content to google!?) but it will have a lot of pages (about 30).

So should I go separate or all in one domain?

Also should I target specific pages for backlinking or the homepage?

Thanks