To check spokes: if you can shake the spoke and it's loose, it is probably broken.

I'm not surprised the tires are still in good shape, but with all that glass on the sidewalks you may want something a little more durable. Or, you could ride on the roads, if you're comfortable with that.

The loud sound is definitely something to try and figure out. Although, if the Schwinn is a cheaply built machine then you may need to replace some major things with higher quality components just to get the trike to run better for a longer period of time.

This [chain lube](Tri-Flow TF0021060 Superior Lubricant Drip Bottle- 6 oz https://www.amazon.com/dp/B003L9K9HQ/ref=cm_sw_r_cp_apa_i_ZgD4BbDKPCEWX) is what the bike shop I used to work at used.

Based on what you've said, a different bicycle might be something to look into. I know you said you have a low income, and that is highly prohibitive. But I would say keep an eye out for any chance at landing a replacement. But for now, try your best to stay on top of the repairs to the best of your ability.

Tri-Flow TF0021060 Superior Lubricant Drip Bottle- 6 oz https://www.amazon.com/dp/B003L9K9HQ/ref=cm_sw_r_cp_api_i_pyOnCbGVEHEYQ I think I’m going to go with this