Tech for Energy
1/ Unknown to me as a 6 year PV installer but if they are that good and big, they should be on review sites like CheckATrade or Which ? Trusted Trader and great reviews of their service should be easy to find.
2/ Not as they have specified – I would run a mile from that. Batteries are more about maximising your PV usage, making system ownership easier to manage and energy security. Batteries cannot really be viewed as an investment and lead batteries can only discharge to 50% to maintain the life of the battery, so the amount of storage capacity is half of what is advertised.
Also lead battery technology is not suited to high peak demands or charging. Lithium is much better suited to this.
Batteries are a good idea if your eyes are open going into it and you know what to expect, but they are not a simple thing to buy, your installer should be open and frank about the technology.