Can I do the following on Wordpress blog...

Can I add an e-mail capture, and add splash pages to a regular wordpress blog (xxx.wordpress.com)?

Or do those add-ons and widgets come when you have a domain.com?

Thanks, I'm brand new to blogging.

nope, you can't. maybe if you buy premium account.

I always recommend going with your own domain, its not expensive at all. you can get a domain for 12 dollars on godaddy or namecheep and I have a hosting coupon in my signature for $1 with host winds or you can go with hostgator. There is a lot of perks to having your own domain. trust, safety branding and although you dont see them, using the wordpress blogger will have ads appear on your "free" site and people dont really like that.

thank you.