Hey there /u/gqtrees

A. If you're just streaming, then you should be fine. The extra harddrive is for downloading games or (with the newest update in June) adding stuff to the Plex Server. Then again, you can always get a external Hard-Drive and add it to the Shield via Adoptable Storage. Downside is that the Drive is locked to the Shield only and you'd have to reformat it to use it anywhere else.

B. Technically, the Shield can use the Chrome Browser if you side-load it and use the controller for mouse navigation, but I don't think you'd really want to do that.

C. See answer above, though I'm leaning towards "No".

D. If your reciever has HDMI inputs, then yes you should be fine, but I'd suggest reading this.

For Dolby & DTS 5.1, SHIELD supports Dolby Digital (AC3), Dolby Digital Plus (E-AC3), and DTS Core Audio Streams in pass-through mode.

http://support-shield.nvidia.com/android-tv-user-guide/index.htm#t=Surround_Audio_Setup.htm&rhsearch=surround%20sound&rhhlterm=surround%20sound&rhsyns=%20

Last but not least: Depends on what you plan on doing. Getting the larger HDD will help with using it as a Plex Server, so technically I'd go with that.

a) from what I am reading, the pro does 4k right? How good is it? Am i relatively future proof with the 4k, i understand it has hdmi 2.0 as well. I can just go with the regular shield, since it has all the same features except larger drive?

The regular Shield and the Shield Pro have identical hardware, except that the Pro has an onboard hard drive and the standard model has just the flash memory. You can absolutely go with the standard model for your purposes, though I would recommend the Pro if you plan to use Plex heavily.

b) I sometimes stream from r/soccerstreams or r/ballstreams. In order for me to do this, I pull up the browser on my computer. Can I do this on the shield?

You have a couple of options. You can sideload a browser (either Chrome or the latest Firefox beta), or install a browser meant for Android TV, and that would suffice as long as the sites use HTML 5 for video. Otherwise, Android TV has built-in Google Cast compatibility, so you can cast the tab from your computer using Chrome.

c) I also have subscription for hboshare which I use vpn for. Can I run xfinity comcast through browser alongside vpn so I can access the content? Will the shield restrict me from doing this? Right now i just do it through chrome browser on computer

I'm not too familiar with HBOShare, and I've never use Xfinity through a browser, so I don't think I can answer these questions. You can certainly use a VPN with Android TV, and HBO Go is available for it, if that helps.

d) Can I run the shield to my receiver?

If your receiver supports HDMI passthrough, yes. Otherwise, you may need to add a USB soundcard.

last but not least, regular shield or pro?

As mentioned, if you plan to use Plex heavily, get the Pro. The current version of Plex has an issue that prevents it from using added storage (even adopted storage) for some functions, including thumbnails. Otherwise, it'll probably be better to get the standard model, and add an external drive or MicroSD card if you need more storage.