You don't have to load historical data - it depends on what timeframe you are using and how far back you want to go.
I am not using the historical data files primarily because I wanted to use M1 signals in my H12 EA's to trigger events, and there are gaps in the historical data files at the M1 level (you will see those gaps because there are large periods where the M1 bars are simply points because OHLC are the same number). I have asked Tradeview about that a few times and apparently later this year they will release a better quality set of historical data files (or right now you can go to somewhere like Forextester.com and pay for higher quality data - I haven't done that). As it turns out I decided to use M5 bars for trigger signals in my H12 EA's and I've got 5 years of historical spreadsheet work anyway (with H12 data from cTrader), so I was content to go back as far as I could go with the data available on the MT4 terminal live connection which is about 12 months for M5 data simply to validate those EA's worked correctly (i.e. it wasn't about getting backtest statistics).
So for backtesting all the other EA's I've developed, I've used the data available on the MT4 live terminal connection. How far back you can go depends on what timeframe you use. For M30 & H1 you will be able to go back about 2-3 years, for H4 & Daily it will be 5-10 years which imo is plenty for most needs.
But there are some tricks to getting the maximum data set on the live connection:
1. What you need to do is open up a new market window - let's say the UJ for example
2. Then you need to select the timeframe you want to use
3. Then de-select the auto-scroll option because that will keep bring the chart back to the most recent time period (i.e. to the right)
4. Zoom out to the highest level (which will make the scrolling process quicker)
5. Then you need to scroll to the left as far bar as the chart will go - keep tryinng when it pauses as it downloads more data - until you eventually can't scroll anymore - then you have the max history you can get on the live connection
Now another tip - the data you download from the live terminal connection using this method stays on your terminal as long as you maintain the connection. If you close the terminal and re-open it, you will have lost the data and need to re-load it - which is a pain (after a while you will get sick of re-loading).
And repeat the same for any market where you want go back back the maximum possible.
Also, you only need to do this if you want to go back further than the automatically loaded period of time. So if you start with a backtest and you select a 3 year period for you backtest, run the backtest and then look on the results tab at the bottom of the tester window and check when the 1st trade entry is - if the results don't back further than say 12 months or whatever that means that's all that's automically available on your terminal, so you will need to use the above loading procedure to maximise the data range.
As to your other question yes I maintain a separate terminal for all my backtesting:
Tradeview recommend you keep it in a different folder to your live and/or demo terminals, but I keep them all in the same folder. You can't rename the terminal sub-folders in the Terminal folder (that I know of), but you can can re-name the shortcuts you keep on your desktop - there is a step in the terminal installation procedure where you need to type in the shortcut name you want to use:
When the terminal installation is complete you will also need to chnage the terminal name on the shortcut icon on your desktop.
Then you need to keep track of which terminal you're dealing with. I keep all my terminals open, but a strict rule I have if I need to compile an EA or access a terminal's data folder is only ever have the compiler or terminal folder for one terminal open at a time and close it once you've finished with it - if you keep multiple compilers/folders open you will lose track of which is which.
