if you want you can convert your blog to shopping cart using woo commerce plugin which is available in wordpress
Use MyBB or SMF and then find a MOD that can integrate the logins between your WordPress homepage and your forums if you want a dedicated community.
bbPress is the closest you'll get to a forum on your WordPress site, but isn't perfect.
If you want then you could but I wouldn't recommend it as there are better alternatives such as MyBB or something else.
Wordpress could be used as a great blog website though.
If you want to host a forum use something like myBB or phpBB. Wordpress is blog engine.
I don't recommend wordpress for making a forum because it is made for something else and using it for making a forum is so wasteful. There are many better scripts like this mybb and phpbb if you want it to be in php and they are working great like what you see in this forum. But if you want to have a more up to date version of forum then there are two great scripts available out there which are really great and have lots of developers. The first one is "Discourse" , it is based on ruby and needs at least 1GB of ram (2GB is recommended) to run properly but it is styled like today modern forums and has many functions for users like sending notification to the browser and etc. The other one is "Nodebb" and as one can guess from its name it is based on nodejs and it is a lot less resource hungry than discourse and it is great with many modern features too. I recommend you to test one of these two if you have a vps and want to run your forum on that.
WordPress is a very good script to create a simple website. It is one of the simpliest to use of all solutions available on the internet. The script as an Open Source should be the first choice for most bloggers,but it can also be successfully used for designing simple websites. However, Operations like removing a date field requires some understanding of PHP language. It is the case for most of such modifications. so using WordPress requires knowledge, and is not recommended for beginners.
Another thing which I don't like about WordPress is that although there are plenty templates available on the homepage, most of them are very alike. It lacks uniqueness. WordPress needs plenty of plugins to be installed. Unfortunately these plugins influence the script's efficiency and not in a good way. Among all the thousands of plugins, most of them have their clones. It means, that any given functionality can be added by several different plugins created by different authors. Sometimes choosing the right one may take quite some time.
Overall, I don't suggest Wordpress. You may look at other options such as MyBB, SMF .etc which are a whole lot better than WordPress, and east to use.