Here are some answers.

Q.19    What was Groo doing in Maringa, and in whatb way did he succeed in
his         task?

        Groo 49 contains the answer.  Groo was protecting the village from
the Wolfmen, but as usual failing as he could not tell the villagers from
the wolfmen.  He made them wear red bandanas, blue shirts and a few others
until he succeede in protecting the village.  This was because there was
nothing left to steal and so Groo left.

Q.21    What was the running joke with M. Wayne Williams?

The price of an issue of Groo doubled so he could only afford to buy every
other issue and wanted his letter published in an issue that he would read.
This started in Groo 90 and ended in Groo 93. C. Houle continued the running
joke in Groo 95 to Groo 97 by asking him not to ask for e repetitive letter
because that meant there was less room in Groograms for his own letters, and
he ended by threatening to send Groo round.

Q.22    What's Mark Evanier's reaction to the words 'Niagara Falls'?

In Groo 109 M.E. starts this one , though he later admits he doesn't know
why.It is something like this:

Slowly, I turned step by step inch by inch I crept up upon him. The next bit
involves strangulation, kicking and huitting him. He then says Oops Sorry
and continues as if normal.  The first time M.E. did the joke it involved a
long story abiout someone taking away his wife and chile and M.E. chasing
them around the world until he caught them at Niagara Falls.

Q.23    When Groo met up with Princess Thaais (Thaiis) for the *second
time*, who is the *last* person in the list of people he thinks she is?

The answer is obviously Groo. Issues 80 to 83 contain the story, though I
think that it is actually the third time he meets her.  The first is when he
is sent on his mission to escort the young Princess through the forest.
Then he loses her but later refinds her and drops her off with the enemy who
imprison her.  Finally when she is grown up he meets her and lists all the
names.  The story ends with Groo going off to look for the younger Princess
that he lost all those years ago.

Q.24    Which Groo story was described by Mark Evanier as 'One of those
where Groo does the wrong thing at the right time, the right thing at the
wrong time...and then finally the wrong thing at the wrong time'?

Not sure about this but I think it is issue 36 'Rhyme nor Reason' where Groo
eventually wishes that the Amulet did not exist.

I'll leav the other questions to someone else as I don't know the answers yet !

Bye for now

Simon P