Explain Quantum Entanglement experiment expected outcomes

is there anything that someone can do at the 2nd location with the other half of the paired particles, that would effect my outcomes (at the first location) such that I do not get a 50/50 measurement.

Yes. He can measure the paired particle at his location, then load that particle into a weapon and propel it toward your laboratory, where it destroys (or recalibrates) your measurement apparatus. But of course he doesn't need quantum mechanics for that. Your question shouldn't be "Is there anything he can do...?", it should be "Is there anything he can do using quantum mechanics that he can't do without using quantum mechanics?". The answer to that one is No.

is there anything that someone can do at the 2nd location with the other half of the paired particles that would affect my outcomes at the first location?

No. There is no action you can do to the second particle that will affect the measurement results of the first one.

Entanglement is a form of correlation. The only way to observe it is to take measurements on both particles, communicate them (using classical, slower-than-light communications) to a central location (which can be at either site), and look at how the two experiments correlate with each other.

Entanglement is weird ("spooky") because, if you assume that the results of the experiments are produced by any arbitrary Local Hidden Variables model (i.e. each particle has a (classical) "state", and they're not allowed to communicate), then there are some measures of correlation (like e.g. the CHSH measure) for which you can prove strict bounds on the amount of correlation possible, and the quantum mechanical results exceed those bounds.

However, that can only be seen afterwards, once the results have been collected in a single place and compared with each other. Without that step of classical communication, the particles are completely independent.