1. All funds should provide a fact sheet with information about historical performance. There are also many web sites which compare the performance of various funds. You can also look up the performance of some european indices. If the fund invests in larger European companies, the FTSE Eurotop 100 index might be worth comparing to your fund.
2. Most of the assets and profits of the companies in the fund will be valued in euros. If the value of the assets and profits (and hence the shares) rises but the value of the euro goes down, then there could be no change in the pound value of the fund. If both the value of the shares and the euro go up (or down) then the value of the fund will reflect both the change in value of the shares and the change in value of the euro.
3. It's best to buy when prices are low and sell when prices are high. No one will disagree with this. What is an opinion is whether prices are high or low at the moment. My opinion is that prices are low but you need to make up your own mind on this.