Hello,
1) We are theme developers and unfortunately we did not study such plugins to recommend you.
2) Go to XStore > Sales booster > Request a quote > enable option and set it according to your needs. Feel free to ask if you need any other guidelines.
3) Sorry, don’t understand your question. Could you, please, explain in more detail what exactly do you want to merge? Do you want to remove space between the Instagram images?
Regards