Would anyone have any experience or any recommendations re choosing a laptop using microsoft word or chrome google documents that has the same grunt as a PC?

I have a son who has a diability and i have huge documents re his requirements, some of which have videos half hour attached for viewing by carers, also huge medication documents with photos.

Also I need to use an ipad for him as the communication program he uses is so far only an apple app and it won't talk to my PC easily so I was wondering what people thought of using the cloud in terms of security? for example if I put some of his medical info on the cloud, how could I stop any one from accessing it? can one have a password and user name only for those who want to view it and if the access is later denied. ( ie a service moves on or we do, can we lock them out from continuing to access info via the cloud? Is the cloud like a sort of google server so I can access info anywhere?

As you see, I am a tech dummy and don't really know anything about technical stuff.

re the phone, if I wanted a phone that could fit in my handbag yet had a big enough touch keyboard to text with, had a good navigating system (ie found the location quickly) , what would you recommend? a Phablet?  I need a phone that has good access to all sorts of apps and one that can take a poratable charger device as they all seem tyo run down so quickly.

Any suggestions would be gratefully appreciated.