It's not much different in the USA. There are limits to individual donations for candidates individual campaigns. It all has to be reported publicly. Donations cannot be given on a quid pro quo for specific legislation. That favoritism could be considered a bribe.
Can you answer my question #2 which I'll bring back into this thread. "2. Can individuals hire what we call "lobbyists" to represent them in petitioning parliamentarians to support certain legislation?"
I could answer if I understood the question. If the question is: do parliamentarians get information from "lobbyists", they probably do, as they do from speaking with others, be it social organizations or individuals. They also actively go around the country to collect first-hand information from workers in certain fields, the people on the work floor.
But if the question is: "do they personally benefit from adopting those lobbyist views and not those of others?" the answer is: not financially. It would also not help their political career, because they don't run for candidacy based on a personal campaign that needs to be funded.
Remember, we have a relatively direct method of electing our members of parliament with a simple kind of direct majority vote, and we the people can choose to elect someone on a low position in the rankings (preference of the party), with a preferential vote. If enough people vote for a person, then that person will get a position in parliament, nothing that his/her party can do about that. We also do not have to register as someone going to vote for one party or another, we decide in the voting booth, who and from what party (currently, 14 different parties have a seat in what you could compare with your Congres). Every citizen can vote for anyone on the lists with all candidates.
So, bad or shady performance in public, is likely to cost one his/her place in politics.
I'll expand individuals to also[...]. Don't they contribute to politicians?
Information, probably yes, money would be useless. Anything over € 50 must be reported and could not be used for personal gain.
Cheers,
Bart