Please capitalize where necessary: from 2006 i especially remember the coldness of may, the storms of july and the constantly grey firmament of august.
A: From 2006 I especially remember the coldness of May, the storms of July and the constantly grey firmament of August.

Please capitalize where necessary: this plugin offers you to take advantage proposed by this website with ease service.
A: This plugin offers you to take advantage proposed by this website with ease service.

Please capitalize where necessary: a bit later on that day, i ended up throwing in the towel, taking off this outfit and putting on a bathing suit and going for a swim in a lake nearby – refreshing?
A: A bit later on that day, I ended up throwing in the towel, taking off this outfit and putting on a bathing suit and going for a swim in a lake nearby – refreshing?

Please capitalize where necessary: we organise guided tours and activities for groups (minimum 10 participants), and we plan the visit to suit your requirements and needs.
A:
We organise guided tours and activities for groups (minimum 10 participants), and we plan the visit to suit your requirements and needs.