No worries MF
With regard to chain tension, I personally like to tension so that if I pull down a chain tooth in the middle of the bar and get it out of the guide bar up to the 'notch' in the drive link with a reasonable force without really yanking on it.
Then check every 10 minutes or so as it will heat up and stretch. Then when you finish, relieve tension as it will tighten up when it gets cold.
Since my saws will see a full day up to 2 days use, then packed away for 2 months or more, which is probably what yours does as well judging by condition, I drain petrol and bar oil, remove side cover and get all the wood chips out, check the oil port is clear, remove the chain and run a piece of wire and spray degreaser down the bar groove to ensure the oil port in the bar isn't clogged.
Sharpen the chain, and grease the sprocket tip, check air filter.
Reassemble and stick a nice wad of paper towel at the bottom around the chain to absorb the 50ml or so of oil that will end up leaking out.
Then next time you use it, its just fuel and oil, flick the paper towel out, check chain tension and off you go
