connections dropping frequently, rate limiting occuring, and packet loss
Without knowing whether your connection resets are injected TCP reset packets or a result of dropped packets, it's hard to say whether you're actually having your data acted on or just having connection issues. It is entirely conceivable that your line or equipment aren't working quite right.
That said, every sane network provider, ISP, hosting facility, or transit provider monitors interface and by proxy customer bandwidth. Bandwidth caps are very common for residential ISPs in some countries.
None of this addresses whether they're inspecting the contents of your traffic, and unless they're acting on what they see in a way that's visible to you by changing how they handle their traffic (or using your credentials, making stock trades on information you email, etc.), it's impossible to tell. Anybody who routes your traffic is entirely capable of sending a copy to second interface.
When it comes to a 3rd party monitoring you on your own network, looking for diverted traffic is possible. When it comes to asking if somebody who is expected to be in the line of transit is doing something more with the data, there is no trace of it until you see them act on it.