Ethernet

In your home, most affordable switches and ports support 1GigE, as do cable modems and routers.  That's not to say the Internet provider will offer you that much bandwidth.  That's Cat 5e.  It's also probably 2x or more what you get from outside.  100 Mbit/s was also something like 10x more than what 96k/24 bit audio required. 

So, it's all overkill.  However, it's best to know your equipment's rated throughput, as bad/slow cables can cause your gear to keep switching speeds and/or disconnect.  So if your gear is 1GigE stick to 5e or better.  Use Cat 6 if your switches/ports support 10GigE.  Again, massive overkill for audio/video.

I hope you mean "Ethernet switch" instead of "splitter."

Keep in mind that Cat 5 cable has about 100x more bandwidth than audio or even video requires.  Going to a higher cat than your source and switch supports doesn't help anything.  Using shielded however may help.

Also, with long runs you run the risk of picking up an induced surge from a local lightning strike.  I encourage you to use a certified isolator (UL60601 or ISA60601) on the side closest to your more expensive gear, or one on each end.  More about that here.