Two things drove my decision to choose 18V Makita. The first was that they had the widest range of bare tools relevant to me and the second was that they had some manufacturing in the UK. I've not regretted the decision. The other trade makes are perfectly fine and I have a variety of 240V stuff...
The voltage varies with charge. A fully charged LI ion battery will read about 4.2V and when fully discharged*, around 3V.
*discharged to a safe level - go too low and damage occurs which can lead to the smoke coming out if charged again.
Agreed wrt the lawnmower but not the strimmer. I have the Makita one. It's a 180W motor but it will only draw this under heavy load. Given that a 5Ah battery is 90Wh the theoretical minimum you would get is half an hour usage from a charge. In reality, it's way more than that. I suspect the...
You might find a suitable hose or adapter / reducer here:
https://www.axminster.co.uk/accessories/power-tool-accessories/vacuum-cleaning?p=3
or here:
https://www.partshopdirect.co.uk/brands/makita/makita-woodworking-machinery-accessories-g53/makita-dust-extraction-accessories-c353/
Makita make stuff in plants all over the world including Telford, England which is one of the reasons I use them. I'd say they are a consistently reliable brand. I've had no issues with them at all and I have a lot of their kit. Also have some Blue Bosch which I'm happy with.
Simple things first. Do you have it in neutral (locked) rather than forward or reverse? (red switch above and to the left and right of the trigger). If so, this is normal. Move switch one way or the other. Apologies if you know this but not everyone does.
I have an old green Bosch and a much more recent Makita. The Bosch is insanely loud, painful to use without hearing protection. The Makita is much quieter although hearing protection still advisable. I suggest that you pay attention to the specs on noise before purchasing.