Hi all,
First off I'm a bit of a newbie so go easy please.
I currently have an ecommerce site (Website A) set up on Hosting A.
I am unhappy with Hosting A because it's slow, unreliable, and expensive.
I want to move Website A to Hosting B (I have some other sites on this and it would reduce my cost too) and here is where I have a few questions:
Can I simply migrate my Website A to Hosting B?
Will this affect any SEO, ecommerce and payment portal functionalities?
I want to redesign Website A as well, would it make sense to announce that the website will be undergoing maintenance, and then transfer the domain to Hosting B and redesign the site?
If I do number 3 will it affect my search ranking?
Is it better to do number 3 on the long run and rebuild the search rankings from scratch?
Is there something I am missing?
I would truly truly appreciate any feedback.
Have a blessed day!

It can completely destroy your SEO if not done properly. But besides that it is not really rocket science.
If done properly your users won’t notice the switch except maybe 15 min for DNS records to propergate.
Regarding 5.: No you absolutely don’t want to rebuild your rankings from scratch. You need to perform a website migration to ensure your rankings get transferred. If your hosting gets upgraded AND your design is better than before then you can even expect better rankings.
This[ site migration guide](https://www.semrush.com/blog/website-migration-checklist/) describes anything you need to know to sucessfully migrate your site. Good luck!
Transfering the website from hosting A to hosting B won’t affect SEO as long as the domain name is same and you make sure the links are working correctly without any redirect errors.
If you redesign the website, there will be some affect on the SEO since the you will Making changes to the layout and content but mirgrating hosting along with it won’t have any additional issue.