Magento Customization

1 - I need someone to help me to fix my checkout page.
I recently installed a free extension *easycheckout* but get some issues on the success.phtml page. looks like is not getting redirected to the right one as a *SID"""* gets added. Also get an issues connecting to my *paypal pro* account though works well with Paypal standard checkout. Before I was using the default Magento Check out page and didn't have any issue however is a bad interface for conversions. I am aware of paid checkout solutions for Magento but wanna try this one first.

2 - I need to complete the configuration of my multiple stores. I have bought 2 domains and I'd like to share the same inventory of my main store. I have managed getting it 50% so far but needs to be finalized.