For our company (we have a SAAS product for university researchers to run experiments online), the big ones that are working for us at the moment are:

- ActiveCampaign (https://www.activecampaign.com/)

Marketing Automation - you can create email campaigns (send this, then in a week send this, and then if they clicked on email A then send email C, otherwise email D, etc etc). I know you asked for sales stack, but this does the first two bullets in your list.

- Pipedrive (https://www.pipedrive.com/)

This lets you manage your sales funnel, move things from stage to stage as you get closer to closing, and so on. Also has automations where you can e.g. change properties on a deal automatically when it moves to a new stage

The other big part is Zapier - in my experience there are TONS of sales/marketing tools and sooner or later you end up using a few and then glueing bits of your process together using Zapier (if they don't have the integrations built in). There are also big, all-in-one platforms like HubSpot, but they tend to be dauntingly expensive for small companies.

In general, we've found that we've needed to experiment a bit to get the internal process right, and then figure out which tools fit us, rather than starting with the tools and bending what we do to how they're set up.

In our case, the basic idea is that if someone interacts with our site and signs up for a newsletter, say, they get put into ActiveCampaign so we can send them an email campaign. If they do something a bit more meaningful (e.g. request for pricing, or fill in a form for a sales enquiry) we might automatically then add a deal to Pipedrive which the sales team can then follow up on.

EDIT: links