Installing a new theme on Magento2

Im looking for a website guru to compliment our IT team with regular short-term jobs. These will include theme design, creation of banner graphics, adding content (supplied by us), adding apps to the site.
Everything supplied by us (except banner design).
Initially we need two themes removing from the site and one new them installing (http://demo4coder.com/bestmart/default/customer/account/login/).
We have 4 websites (each with own domain) within the one Magento installation.
All products and setup of shipping, payment is already done and will be completed by us ongoing.

Are you available to;
1. Remove the two themes which I dont like and clash with each other
2. Install the new theme that I have purchased and the extensions within it
3. configure the CPanel and .htaccess so the four domains point to the correct website within the one mangento installation

Base domain is www.browserswelcome.com

Thanks