Aegist first of all thank you for your honesty and obvious wish to do the right thing. If only all vendors were like you.
Your questions are also very pertinent given the changes recently made. I would be the first to admit that despite the revised guidelines the new stance on advertising has not been forward tested and as such not every issue is going to be covered in a black-and-white manner. Your questions raise a couple of such grey areas.
We appreciate that there is a difference between a full-on commercial site that directly sells trading-related products or services (e.g. a system vendor) and one that does not sell anything of the sort, yet may still (in the future) benefit from traffic, e.g by way of adverts.
However for the moment at least, both these types do unfortunately fall under "commercial web site" and as such even the most modest hobbyist or blogger who stands to make £0.84 from Google ads per year is still considered as a vendor. The administrators are currently discussing ways of making this situation a little fairer and clear up any confusion, perhaps by way of a new vendor category or different icon.
To answer your questions. I'm afraid links in signatures are not allowed. Actually they never were. The guidelines are fairly strict on this matter:
"It is not permitted to use the signatures to advertise. Signatures may not include any link, identifiable URL or Email address."
(Although very occasionally links to worthy nonprofit organisations are allowed to stay, at the moderators' discretion).
On topic references to your own non-product information website? Yes, no worries there, as long as you are not doing so merely to promote it. Obviously this is a matter of discretion for the moderators too, as one man's cynical promotion may be another's useful information. If you were, say, a trading system vendor and you kept mentioning your site then that would be out of order. But if the site, as yours does, contains only free information, then I see no harm in mentioning it whenever it is pertinent to the discussion.
Avatars: Hmm. Glad you pointed this out. Having quick checked the guidelines I can see no reference to them, which will have to be updated. But I also know that when someone's avatar has proudly displayed "4000 pips per month www.leechfleecer.com" fights have broken out between the mods to see who can delete it first. So, for the moment it's gotta be no, not allowed, sorry. I have had a look at your web site and I understand that there is little commercial about it (yet), but at least you still have the www button for people to have a look at it.
Sorry to sound so harsh and thanks once again for raising some useful questions. As ever site policies are organic and can be changed as we gain practical experience of them. Feedback is very useful in this regard.