I was originally taught by my SEO sensei that you can include 1 link for approx. every 100 words. Still, I wouldn't do more than 1 or 2. You definitely don't want to include more than one link to the same page. Here's a video of Google's (former?) Matt Cutts on that.

Be very careful when guest blogging for links. Here is what Cutts had to say about Guest Blogging:

I wouldn’t recommend relying on guest posting, guest blogging sites, or guest blogging SEO as a linkbuilding strategy.

http://searchengineland.com/matt-cutts-stick-a-fork-in-it-guest-blogging-is-done-182147

If you are guest blogging for links, I would suggest reading Cyrus Shepard's The Rules of Link Building here on the Moz Blog. He states that you should never ask for the anchor text, and I agree. Worry more about the quality of the content and less about the link.

If you're really worried about content duplication, I would do as you suggest, placing them as an image. Personally, I wouldn't lose sleep at night if I copied and pasted some reviews from my G+ Local.

(Former?) Google employee, Matt Cutts once posted a video claiming that duplicate content won't hurt you unless it's spammy. https://www.youtube.com/watch?v=Vi-wkEeOKxM&feature=youtu.be

If you're still on the fence, what I would also suggest is to try asking the same question at Google's Webmaster Central Help Forum. I think you'd get a fairly definitive answer possibly from a Google employee like John Mueller.

I've had SEO consultants swear that you should still fill out the meta keywords tag because some search engine in a galaxy far, far away is apparently still giving it some clout. I say leave it blank. The search engines that matter won't give you anything positive out of it, and you never want to find yourself in a position where you're actually getting dinged for having that field stuffed with too many keywords, or having the same keywords duplicated across every page.

I also agree with Donna that it's making it easier for your competitors to see what you're targeting.

If you ever have a client who demands to know why you're not including meta keywords, you can show them this blog post directly from Google that pretty definitively states that they have no ranking value: http://googlewebmastercentral.blogspot.com/2009/09/google-does-not-use-keywords-meta-tag.html

I would optimize the pages that you want to drive traffic to for keywords that are naturally relevant to each page. Never stuff a page with keywords (use your gut to determine the right amount) and always write copy so that it is completely readable and not awkward for your visitors. I would also avoid creating multiple pages just for the sake of targeting similar keywords with no other purpose (e.g. you have a page that targets "red apple" and a page that targets "red apples"). I've seen sites get smacked by Google Panda for doing this.

Sites with poorly-written SEO copy seem spammy and will be an instant turn off to whoever's showed up at your virtual doorstep.

Pages such as Contact Us and About Us don't really need optimization per se. However, all pages should at least contain unique and relevant h1s, meta titles and descriptions. Also, always avoid duplicating text between pages. This helps your website be more search engine friendly. I find that the Screaming Frog SEO Spider and Google's Webmaster Tools HTML Suggestions are great for diagnosing which pages on your site need these unique elements.