1. The volume in the tick: is it the shares traded that day, the number of lots, or the rupee-value traded that day for the stock? 2. The last traded price: does it give the average price of the last trade if it was matched with multiple orders, or just the last leg of it? 3. If the lot size information is used anywhere, where can I find it? 4. How far does the historical data go for stocks?
A last traded price is the price at which last trade happened.
You can find the lot size information in the instrument master dump. You can know more here.
You can check out this thread to know more about availability of historical data.