You know what the hardest part about your questions are? It's that there really is no one answer. Home schooling is, in essence, a customizable educational system from the parent to their child. Because of this, it's hard to give anything but a general answer to most questions regarding it because each family has their own unique way doing it. I've been home schooled up through high school and am now in college, and in those years I saw everything from the very relaxed and laid-back styles to the incredibly busy. Some of my friends had only 3-4 hour school days while others were literally going from right after breakfast until dinner with every other weekend filled with extracurricular activities. So yes and no. Depending on the family, you could have more free time or less than the traditional schools. (My experience had it more in between the two extremes with 5-6 hour school day while getting a little longer in high school because of group/community college classes)
As for socializing...That hasn't been a problem for the most part. Yes, there are families who I believe shelter their kids too much through home schooling. It's unfortunate, but every system--Whether it's home schooling, public, private, charter, etc--Is going to have it's freak incidents that are not considered normal to any degree. Most home schoolers have opportunities to be with people on just about any given day. Sometimes it's through group studies for a given subject, sometimes its through extracurricular activities, sometimes even through public school systems! In high school I was seeing a group of friends every day during the school week. So yes, while it's a valid concern, there's plenty of opportunities out there to get out and meet/socialize with others.
As for who teaches, again, that's really up the individual families to decide. Most of the teaching comes from either one or both parents. For me, my mom taught me my core subjects, and then in high school I would get together with other home schoolers for a group class. In these classes, the mom or dad who had a major in the specific subject (like mathematics for example) would teach us in a traditional class setting...Just in their living room instead of a classroom. I also took community college classes for some subjects like Spanish and science.
And yeah, it does sound like it would be a really weak education coming just from our parents, but remember, they went to school too! Also, it's not like they're teaching from scratch. There are hundreds of programs, curriculum and text written specifically for home schoolers that provides the framework for each and every subject the parent needs to teach. Most of them include parent/teacher guides, student textbooks, and even supplementary activities. So it's pretty well covered.
Sorry for the lengthy post, but I wanted to give my two-bits worth as well as mention that all we can do is give general answers to your specific questions because it's different and unique for every family.