Yep.. as you can see, in my own perception they are just similar. If you have a blog and got a recent post in your sidebar, it act as your sitemap for me... If search engines crawl your homepage and saw the recent post there, in my very own perception, It will act as your sitemap.. Correct me if im mistaken..
Definitely RSS feeds ... it will add some traffic to your blog .... It is not necssary to have sitemap .... The inner links in your site can act as sitemaps
What will be the problem if you'll going to have both..I think there is none...but for blog its rss due to all the links of your post are being archive on your side bar.so it's not that important to have a sitemap for a blog..
I've never used a sitemap. To me, it's not necessary. I didn't really use RSS feeds either but a couple of my sites had it built in nicely so I didn't want to get rid of it. It brought in a ton of traffic.