While doing research after a plane crash near our village I zoomed in on the navigation from both German and RAF pilots. I have some questions about this.
The question is folowed by what I have made of the information I found in several sources. So I don't know if it is all right.
Please shoot on the story and If you can provide me some answers

German used in the early years of the war the so could Knickebein guidance to find their targets and became very accurate in hitting their targets. The system was based on the Lorentz Radar that was used since the early 1930's. After the British discovered the working of this system they switched to X- and Y- Gerät. The British could detect Knickebein and send false signals so the Germans drop their bomb-load to early or to change the route of the plane. (German flyers landed on Britsh airstrips thinking they where back in the Heimat) The X-gerat was harder to crack but this was also accomplished.
Then in 1942 RAF has suddenly GEE (which looks a lot like Knickebein, except they use more stations to create a grid across Europe) Just after X-Gerät is cracked... RAF suddenly has OBOE.....

Now the question...
Did the RAF had radio/radar navigation before 1942.
I can't find any information about this. Some sources say the RAF pilots flew on maps and the stars... The German on instruments. When instruments crashed of where compromised the German pilots became in trouble because the younger ones couldn't navigate without instruments.

Question 2
Did the RAF use the German way of navigation as a startpoint for their own systems... This means the German were superiour during the first 2 years of the war as for plane navigation. In 1942 the navigation techniques follow each other in a fast way and gave Harris the chance to modify the way of bombing... Because not everyplane had a radar this lead to Pathfinder Force... (The Germans used a similar solution for their Knickebein raids).

Question 3
Did the Germans had something like a groundradar similar to H2S
The H2S radar was born by coincidence. They where developing a radar extender when they found out it showed the surface beneath and infront of the plane. The Germans didn't had something like that.

Question 4:
When started the RAF to fly in Streams...
The German had the Kammhuber linie. I thougth this was the line at the German border on which Searchlights, radar, Flak and fighter planes were used to attack Bomber Command planes. It seems their where multiple stages... A himmelbet bereichs near the coast (Netherlands, Belgium, France en Danmark) where radarguided interceptors attacked the planes, A "Hell riegel" with searchlights and flak near the German Border and some special zone's near Berlin, the Ruhr Area and some other area's where radarguided fighters and flak were used against the bombers.
When the RAF found out the German radar could only follow one plane at one time in these area's they decided to fly in streams...