I wasn’t quite satisfied with the situation, too (but actually because there are only the latest 30 active questions). So, I was attempted to put a feature-request onto Meta.SE. Luckily I did a search for rss-tagged questions first and found this recently asked and answered one: How can I get more then 30 feed items?
After a short try & (typing) error I found out, that this works very well:
(for RSS readers one should probably use “body=true”). As you can see on the Stack Exchange API documentation page there are lots of opportunities for other feeds, e.g. only for answers or only for comments or … The selection by tags works, too. The “pagesize=100” is the maximum and shows me today questions back to about 45 hours.
For meta.tex.SX it also works: http://stack2rss.stackexchange.com/meta.tex.stackexchange/questions?body=false&pagesize=100&sort=creation
If you find this useful, please upvote the original answer in Meta.SE as well, if possible for you.