There are so many places to get lamp post signs that it is unbelievable. Lots of good recommendations here or you can go to enther square on vendor night and a lamp post sign vendor will be there or you can visit Market of Marion where there are several vendors offering these signs.
No rule against putting your house number over/near the garage door. I did it. I kinda like it.
I opted to put full names on our sign. Your point about caution is valid but, IMHO, a little overkill. Knowing your house number, lots more info that your last name is readily available to anyone who wants to spend a minute or so to look it up. Why inconvenience friends, relatives or neighbors to defeat some scumbag whom you will lose to anyway if they set their sights on you?
As far as recommendations for a landscaper go, see yesterdays The Daily Sun (Wed, 4/06). The supplement to the paper was the VHA monthly newsletter and on page 3 of that supplement was a good article from Seniors Vs Crime on landscapers, how to pick them, and how to deal with them. It is well worth the read and full of useful info (but no names of companies).
You probably already threw out yesterday's newspaper but no problem. The Villages Voice, which is the name of their newsletter, is online. You can get to it by going to the VHA site at
http://www.thevha.net/. One of the links on their home page will be The Villages Voice (their monthly newsletter) so click on that and select the April 2011 issue and you will find the SVC article.