Search Engine Friendly (SEO) Url's and Special Characters (&$£!"[:]~#?) - Url Length & Other General Advice

I am looking for information and general advice on the use of special characters in the url of my pages and what the implications are in getting picked up by google and search engines in general.  In particular, I am looking for confirmation if the use of the following characters will prevent the search engines from spidering my site (or if there are any penalties).

£
$
~
#
[ ]
( )
:
;
?
| (pipe)

Some urls may have accented characters;  /capcom-gámé-3-(ps2).html  - good or bad?

From what I have seen on our website, the characters : [ ] ( ) | ? have already crept into the urls.  I am aware that the ? sign usually means crawlers want to stop reading after that, but what about the others?

Which is better from the following:

1 - site.com/directory/photography/digital-cameras/sony/cybershot-t100
2 - site.com/directory/photography/digital-cameras/sony/cybershot-t100.html
3 - site.com/directory/photography-digital-cameras-sony-cybershot-t100.html

Lastly, is there any limitation on the length of the url and it being prevented from coming in the search results?  I like to include full descriptive paths in the url to help people travel down the 'breadcrumbs', but is there a general guideline on where to draw the line.

I understand there are many questions here, but I am looking for general advice across the range, and hopefully some confirmation regarding the use of special characters and which ones to avoid.

Thanks!Start Free Trial