Help needed on choosing POS and integrating with zettle

[Pwts]

Hello. I am a very small bricks and mortar shop (UK) who wants to start selling online but on a very small basis. I don't have any staff and don't plan to get any. I have the basic shopify annual plan, I have bought a theme and the design is ready to go. At the moment in my physical shop i have a zettle card payment machine. I am considering getting LITE out of the POS options but I would like to know two things first...

 - Can i integrate zettle and LITE successfully without too many dramas? I am worried about duplicated sales etc.

- Will i still be able to offer local people free collection from the shop? It seems to suggest not. 

- Does (as an alternative) opting for PRO mean i would have to buy shopify hardware?

I have been getting conflicting advice every time i have tried to talk to the shopify advisor over chat. I am almost ready to give up entirely to be honest. I am finding the jargon overwhelming and the help dismal.

Any help or wisdom welcome, please.