Different plugins will serve their own purposes. For example, an ecommerce plugin would only affect ecommerce-related pages (products, shopping cart, etc) and a landing page plugin would help you build landing page. They shouldn’t interfere with one another.
What is the problem you’re having?
Great, thanks for the help! I’m learning this from scratch but am determined to create something.
I’m trying to set up an ecommerce site (have a plugin for that). In the mean time I want to have a landing page while I build interest. The landing page will have information for sellers while I build the site. Once the site is complete I plan to keep the domain.com/sell page only changing the “sign up for updates” button to a “sell now” button.
That seems like a solid plan. I’d suggest using something like MailChimp to collect addresses on the landing page for now, as it’ll give you a good platform to use to send messages to them as needed.