The three UAs are valid but it depends on the context - they may still cover bot activity. iPads are a nuisance - I block a few due to faulty headers: one day I'm going to have to work through the rejects and see what's wrong. :(
Squid is a common linux proxy. I usually find that either the Forwarded-For is the same as the IP (valid); or it is a local IP (eg 10.n.n.n - often but not always valid); or it is a server farm trying to get past a block (NOT valid); or it's something like G or Y trying to forward for a so-called customer (sometimes valid but they often get blocked due to a previoous customer not being valid).
220.127.116.11/18 is Hostway - see comment above re: server farm proxies. Ditto I have two /19s blocked as servers in the 66.185/16 range. I would guess a lot of those you are seeing are from server ranges.
Do you run a Linux machine? If so try Umit. It allows you to send out requests for port information on remote computers - slightly unethical except when THEY hit you first! :) There used to be a Windows-resident Sam Spade but last time I used it, many years ago, it had begun failing IP resolution: too old and not updated. There are probably other windows tools.
Thought: if you run windows desktop but a linux web server you may be able to install Umit or run a similar service via a PHP library.