New speakers in 6n2. Need help with a few things

Hello all.

Recently redundant and needed a new car very quickly (had company car) So I have become the new owner of a W reg polo with only 60,000 miles on the clock and full service history! 2nd owner in grey, pristine bodywork for £200.00

it’s a 6n2 and I feel very lucky. Alrhough it is old…
 

My issue, and virtually the only issue.

Drivers side speaker is not working and the tweeters crackle, so I have purchased some pioneer replacements.

I have read before taking the door card off you need aftermarket speaker fitting brackets.

The brackets are identical to what looks to be already there and the speakers I purchased have the right notches around the edge and I have used the existing screws and holes. Was this a bad idea?

there is a lot of foam already on the door. Looks original and glued on although someone has clearly had the door card off before as the handle I found was already broken away from screws and I’m missing several clips…

Back to the point. I don’t feel the new speaker is as good as the old one which is currently still in the passenger side…

The new pioneer I believe has vibration, which I think is more to do with the fact I need replacement clips on the door card perhaps…

questions.

1) I need to know where to get these clips quickly and cheaply, they are U shape black circles, fit over a white plastic plug if anyone can help with that…

2) Do the foam pads for speakers help?

3) should I have used the aftermarket bracket, which looks identical to the foam shape already there?

3.5) should I remove the foam when fitting the brackets if they are needed?

Any help would be appreciated.

Thanks