Tree algae around shut lines & Inside condensation

[Vx-Mad-G]

Just after a bit of advice here please.

We have a white Astra-J, and have noticed the last couple times I have washed it that around the ***** lines I get loads of dirt splutting out, especially when jet washing ot hose piping.

I have also notices some greeny tree algae around the tailgate shuts, especially around the top side.

Whats the quickest and most efficient way to get rid of this without splashing the inside of the car?

In addition, im notiticing the inside of the car getting lots of condensation, and when its icy outside, even surface ice on the inside of the windscreen.

There is nothing wet inside the car, seats are dry, carpets are dry, but it just baffles me.

Can anyone help with both issues please?

Thanks.