Most teacher bloggers use Blogger which is a free site that hosts your blog. Blogger gives you some choices in templates (but they aren't that cute). Lots of websites have free Blogger templates to use. If you Google "free blogger templates" you'll find all sorts! One teacher created a Sqworl page with all sorts of blog design resources: http://sqworl.com/7zc3he
I create my products primarily in Microsoft Word and save as PDF when needed. I also use a graphics program to create some of my worksheets and things.
I don't have any children, so I am able to devote a lot of time to my blog, FB page, etc. I only started selling on TPT at the very end of March 2011. I didn't make as many new items while school was still in session. I have been creating like crazy since school got out.
For me it is worth it. Since April I have made over $3,000.00 I never believed I would make that much. It has taken some work though. You really have to network with others and promote yourself and your items/blog. If you just post on TPT and never blog or comment on other people's blogs I don't know how much success you will have. You will develop a greater following by having an active blog.
There is a great online course (30 video lessons) that tell you how to go about marketing yourself and creating a following for your blog and products. It is well worth the money to learn a lot of inside tips and develop your blog.