You should diversify your backlinks, build different set of link to the main URL and internal pages with varying anchor texts.

Most backlinks out there are to home pages, not to internal pages. It would not look natural if you built links contrary to that. I'd build most links to my home page (meaning greater than 50% at least) supplemented by links to internal pages.

Build links to the pages you want to rank.

Diversify sources and anchor text to avoid penalties.

It depends if you want to just rank the homepage.

If you target other keywords with the inner pages then build links to those as well.