i prefer deep linking if you haven't that target keyword in your home page , But if you have that keyword in your home page too then both are fine
It's all about balance. On the one hand, it is necessary to gets links to internal pages containing the exact information the prospective visitors are searching for. On the other hand, it would be silly to give up homepage links altogether. Therefore do both kinds whenever you get a chance.
Both are important. The higher amounts of backlinks should be pointed to you sites main URL. Adding deep links will promote link juice to internal pages of your web site. This will not only boost the deep linked page, but also add Pagerank to your whole site as well. Link Juice will flow to the site as a whole intern by your internal linking structure. Look at the simple page a b c PageRank diagram on the internet and you can see how all three (links pointing to main URL, links pointing to internal pages and internal link structure) will work together. I did an internal link structure change and now can see link juice flowing to specific pages on my site.
I will say both works fine, it gives you energy to diversify your keywords, home page can have 4 keywords your targetting, while deep links can target other keywords too. So i'd say both do the treat. More traffic, More sales.
Yes, it will help, there is a strong probability that person coming to deep link may also visit your home page to know about your services. On contrary, person visiting home page may not go to inner page of your site that's why we need promotion of inner pages of a website.
From my experience it is a toss up both will be fine. But if it is a phrase you are targeting i tend to deep link. But I try to get at least a few links to homepage first if I can.
I have been under the impression that a 75% homepage to 25% deep linking is a good percentage. Yesterday a post here on DP claims it is best to have 80% deep linking to 20% homepage links? I think a 3 to 1 homepage to deep links is still a good "rough" percentage to try to stick to. Getting deep links on long tail keywords can result in page 1 results on lower trafficked pages but more likely to purchase click throughs
As others said... If you are building a variety of links, it is good to mix it up. You want a strong homepage, but deep links can be very beneficial as well. Be sure you have a navigation that lends well to pagerank flow... Having breadcrumbs can be useful for this.