Bonus in welcome e-mail

If I'm understanding you then the solution to your problem is simple. You have a couple of choices:

Create a pdf report or a video on a topic that would interest them. Make sure the quality is high or you'll probably end up with a lot of unsubscribes.

If you don't want to create your own lead bait (gift) you can always do a search for "your niche PLR" and purchase previous created content to give to your subscribers. Just make sure the PLR content is high quality and at least do some editing before you make it available so it is somewhat unique.

Ensure that any email you send provides value. Put yourself in the subscriber's shoes. Do you want to receive nothing but sales emails? Probably not. So even when promoting products to your list make sure that your product recommending actually solves a problem your typical subscriber is having.

In terms of creating multiple lists - try to keep things simple. You probably don't need to have an existing subscriber opt in again for another product that you own. Just send them to the download page.

The two main categories you want to have are free subscribers and buyers. Your free folks are gold and your buyers are platinum

Best of luck to you
Ricky

It depends on the niche you re in, and what your promise on your squeeze page.
About a link in your welcome email, i would advise you to do it!
I am doing it, and i get some good sales from it.
Of course you don't just put the link there say something like"..since you ve joined my list, i understand you re an action taker, and you want to make money easy and fast, this is why i strongly recommend you to check this out(your link), it will help you to..etc"
Of course this is what i use in my niche, MMO, you can make it accordingly to your niche