I would try and stay clear of doing this to be honest. It won't validate, older browsers may have problems with it and I'm not sure how search engines would treat it (they may not follow it). There are better ways to do it.

If you set your anchor tag to 'display:block' you can then set the height and width too. This way the whole div would be the link, not just the text.

I've recently undertaken the same task and I decided to make a decision based on the quality of the directory. If you currently have a low amount of back links with your brand/domain in them then changing the anchor text on some of the links will definitely help you build a more natural and strongly branded profile.

Install a page rank toolbar if you don't have one already and check the PR on the home page of each directory. If it comes up as 0 then rather just remove the link (if possible) as it's either a low quality directory to begin with or it's been totally devalued by Google.

You don't, your IP address may be recorded by the site you have submitted the link to but not by Google.

However, if you are using proxies then you are probably doing something questionable in the first place and there is a chance you will get into trouble anyway. Especially if you are creating 200 links per day, they will notice this as it wouldn't look natural. It sounds like you may need to focus on a more natural link building strategy if you want your site to stay in the SERPS long term.

I think they only pay attention to the anchor text of the first link, this would stop people from stuffing multiple links to the same page each targeting a different term. So if you have a few text links to the same page make sure the first one contains your primary key phrase.

Nofollowing the rest of the links wouldn't have any positive effect. The total link juice a page can pass on is divided by the total number of links on the page (regardless of follow or nofollow). In fact it can have a slightly negative effect as the juice from the nofollow links essentially evaporates instead of being passed to other pages on your site. Here is an article on how this works.

http://www.mattcutts.com/blog/pagerank-sculpting/

Did you read through all the comments? There is a lot of useful information in there. Here is another article by Rand shortly after the update that describes how this will affect websites:

http://www.seomoz.org/blog/google-says-yes-you-can-still-sculpt-pagerank-no-you-cant-do-it-with-nofollow

Here's a simplified example: Say you have a page with 10 links on it, this page is essentially passing on 10 points of Page Rank (PR) to other pages on your site. If you nofollow 3 of the links you are only passing on 7 points to the rest of your site, the remaining 3 points evaporate. If you have 500 pages on your site and you nofollow just 3 links on each page then how much of your PR are you wasting in total?

This is why Matt recommends that you let your PR flow freely through your site. PR sculpting using this strategy used to work before they made this change in 2009.

Of course this is still down to interpretation and how much you believe what Google says, obviously they don't give away too many secrets. This question gets asked in this forum every week and I would say the vast majority of the SEO experts here  advise against this practice.

I hope that helps