Depends on how much. If a tiny amount, it should be fine. If large patches (inch or larger) you may have issues.

Typically yes.

No one has a true black semi-transparent. Darkest would be Espresso in Armstrong Clark or TWP 1504 Black Walnut. You can get samples here: The Seale...

A deck cleaner and would brightener will help the stain to penetrate better. As for a stain, look at a penetrating water-based stain to help with your...

No issues. Just do it in spring.

As long as you prep correctly you should be okay to stain now. You can also wait until Spring. See here for new wood tips:/p>

Spray it on with a pump sprayer. You will have to do this to all your wood.

Try 1 part bleach to 4 parts water. See if that kills it as it looks to be internal.

1200-1600 PSI with 25 or 40 degrees tips. Using a deck cleaner as well will help.

Pressure wash with water and brighten the wood should work.

You cannot spot clean. Best to do it all correctly in the spring.

No, but prewet the siding first and then rinse over spray while working. This makes cleanup easier.

They are all bleach based at the big box stores and not very good overall. We do not suggest any of them.

2-3 years with a semi-transparent is the max you will get:/p>

You cannot use a transparent stain over this solid stain unless you power sand off the current coating. That is not easy to do.