Upgrading Drupal

I have multiple instances of Drupal set up under one hosting account with a main domain (carolinabrewmasters.com) and the others as subdomains. They were all working nicely on version 7.10. I updated all of them to 7.12 and now I am getting an error:

Warning: mkdir() [function.mkdir]: Permission denied in drupal_mkdir() (line 2336 of /hermes/waloraweb026/b1054/pow.carolinabrewmastersc/usopen/htdocs/includes/file.inc).
The directory /hermes/web11c/b1054/pow.carolinabrewmastersc/usopen/htdocs/tempdir does not exist and could not be created.

I have just taken over as webmaster of a Drupal site and checked the update status. It needs an update to the core files and also to about 25 modules. I think I can understand how to carry out the updating to the core and individual modules but I would just like to ask if all the modules can be updated at the same time, running update.php once after uploading all the new module files. Or do I need to run it for each individual module?

Thanks
Mike

L.S.

Our company has an external company which build and hosts our website.
We now receive an email of the company that a security update is necessary.
Installing the update will take them 2 hours for which we need to pay 250 euro's.

Obviously, i would like the security update but our company has limited funds for the website.
Therefore i would like your opinion....

I've problem for long time.
In the comment module, they are an update that won't run (I expect that I've run it but not finished it). It's update 7007 :
function comment_update_7007(){
db_add_index('comment', 'comment_created', array('created'));
}.
I've try to delete the "comment_created" index, but "ALTER TABLE comment DROP comment_created" return "ERROR: column "comment_created" of relation "comment" does not exist".
if I delete the table entirely, drupal fail :-(

I am attempting to run updates using Drupal 6 with hopes of upgrading to Druapl 7. I am using a PC. I am unable to download a gif or zip file. Does anyone have any suggestions for PC users? Thanks.

Hello, This is first time to post in forum, so if i'm in wrong place please point me in right direction!
After updating to these modules;
computed_field-6.x-1.0
faq-6.x-1.3
genpass-6x.-1.4
ms_core-6.x-1.19
views_bulk_operations-6.x-1.13
on my site running D6.24 Web server: Apache/2.0.52 (Red Hat) FrontPage/5.0.2.2635
I ran update.php successfully. However when I then ran update.php on the shop site, which is a sub domain, but sharing the same db I got the following error messages: