Re the insects, it depends quite a lot where you are in the country and which type of forest you're in and a bit on the weather.
As an example, here in central Finland, the mosquitos aren't too bad right now, a good repellent (50% DEET) on exposed skin will do the job in 95% of situations.
In contrast, we were a week up in Kainuu (just into the northern reindeer herding area) earlier in the summer, and we needed the head veils for trekking.
On top of the mosquitos, there are many varieties of gadfly/horsefly, the females of which happily bite a chunk of flesh from you - these can be quite painful. And later in the year we will have the moose fly, which lands on you and sheds it's wings - last year one cheekily tried to set up home in my chest hair! I only felt something was wrong when he sprinted across my nipple.
Taking a daily anti-histamine tablet (loratadine or similar) also helps and we tend to carry an "adder pack" when we are out and about. This is a pack of 3 strong hydrocortisone tablets, intended for an adder bite, but equally useful if you are stung by bees or hornets.