What is loinen?

Loinen can be translated as parasite but only in the sense that these people did not have their "own" place to live. They were probably at the bottom of the economical status order, but you shouldn't look at it as a sign of disapproval. Just a classification.

How can siblings have different family names?

Between 1880's-1920's family names in western Finland became more common among general population. (People with education and trade people in towns had family names already in 1600's.) During this period the adoption of Finnish names (as opposed to the Swedish and Latin ones used previously) started as well.

As the name conventions were loose, people chose names without rules or traditions. Personally I find it waste of time to wonder why
a) children chose different name than parents
b) siblings chose different names
c) a particular name was chosen
d) people would change names several times

because all that just happened.

(In Eastern Finland common people have had family names 1500's which is an uncommonly long time in European context.)

You can read more at http://www.genealogia.fi/emi/art/article216e.htm

Where to post a query?

A general hint for discussion forums is to
a) Check the amount of activity. Low activity means that there is less chance to get a reply.
b) Check the quality of replies.

On the forums relating to Finnish genealogy in English there are usually few people answering and more asking questions. If the previous queries are unanswered or answered poorly, then you might want to try some place else.

Alternatives I am aware of:

• The Finlander Forum was originally focused on the Swedish speaking areas of Finland, but I think it has widened since then. Active.
• Ancestry.com message board for Finland has Americans posting and only a few people from Finland checking in. Linked to the Rootsweb Finland mailing list
• Yahoo Group FinlandGenealogy is not very active, but people usually get a reply.
• GenForum for Finland reasonable activity.
  

General tips to making genealogy queries apply. Give enough information, state what you are looking for or what is the problem you have. Personally I take issue with people who post queries without checking any information about Finnish genealogy before hand. They either

a) do not have enough information to "jump the pond", in which case the only thing to say is: you need more information, go and try to find it
b) do have enough information but do not explain why they are not proceeding with the research.

If you are simply looking for someone to do your genealogy for you, there are professionals for that. More on finding them later.