I link back to my website via my company name on the footers of sites I develop.  Lately I've been changing this to my keyword and mixing and matching.  This has been done for new sites I create and old sites

I've not seen any benefit so far after a couple of months.

Most my clients are hosted on the same server as my main site that it links back to.

1. Is this a bad idea to link back on the same IP?
2. Is footer backlinks to the main developer going to annoy Google?
3. Should I change my main site's server, will it help?

All my competitors seem to do it and as far as I can tell they seem to get better results than I do.  Because I'm now changing them the reason I see no benefit?

Thanks