That's not the same thing at all. Especially as LLM's get smaller, WhatsApp can make a lot of money reading your messages and listening to your calls on the endpoint in order to market segment your ads while remaining e2e encrypted.

Signal isn't backed by a global data gathering conglomerate, so no.

Yes, in proportion to the number of times they bring it up in a conversation.

Yes

Sure you should be suspicious. You should always be suspicious. Especially if it's free. And you can do something to calm your suspicions. Like checking out Signlas Open Source code.