Module development and code questions

I'm using the organic groups module with a few (mainly cosmetic) modifications I've made to it, but I want to be able to let each group (whether through this module or another one) maintain nodes whereby everyone in that group can edit any node that belongs to that group, presuming the author of a node allows that. At the moment the functionality for group-based editing seems non-existent, no?

In other words, when submitting a node (perhaps only of certain node types) a user of a group can choose:
- Only I can edit this node (unix 'chmod u=w node')
- Anyone in the groups selected below can edit this node (unix 'chmod ug=w node')
- Anyone, even not in this group can edit this node (unix 'chmod a=w node')
... i.e. similar to unix's -w--w--w- permissions

Organic groups already deals with the 'r'ead permissions. You can set whether a node can be viewed by everyone, or only people in the group - that is sufficient for read.

Ideally I'm also looking for some wiki functionality here as well, whereby one can revert to a past revision of a node.

Has anyone done anything similar to this already, or can anyone point me in the right direction to achieving this? Perhaps there's a wiki module which I haven't come across yet that will sort of achieve this (they all seem to just do input filtering at the moment to format links)?

I see thiere's this node ( http://drupal.org/node/5618 ) where people have discussed something similar in the past, but it doesn't look like it came to anything.

I'm confused. Flexinode module says:

"You may define your own content types here. These will be extensions of the basic "story" node type with additional fields that you specify."

But the 'story' node type includes a body field... flexinode doesn't (just a title field by default). Sure, I can add a 'textarea' field, but this isn't ideal. In particular, when a teaser of my new node-type is shown, it has

"Body:
this is your body"

... which is ugly. I don't want the 'Body:" part.

Any ideas?

Whilst developing a module, particularly whilst I'm hacking away at the organic groups module, I need keep viewing how the site looks for various types of users, i.e. preferably by having a different browser window open for each one, e.g.: superuser; organic-group admin; regular user; user of a different organic-group; anonymous user.

When I enter a search term in "amazon item import", and hit "Search" I get a solid white blank screen. I have read all related posts on this site, but I can't seem to solve this.

My error log shows the following error:

...PHP Fatal error: Call to undefined function: domxml_open_mem() in /home/httpd/vhosts/harkeydesign.com/httpdocs/modules/amazontools/amazon.php4.inc on line 318, referer: http://harkeydesign.com/admin/amazon_import

I'm considering moving to Drupal from my custom PHP driven setup. One of the things i've been trying to add to my site is an industrial scale collection database/trade facility. It's about 1/3 done, and i'm trying to decide if i should just scrap it and implement it as a module in Drupal, so it might benefit others, and in turn benefit from the other modules that exist. My questions at this point are many:

1. Does something like this already exist?
2. Is the learning curve to begin to do something within Drupal steep?
3. Is this kind of thing best implemented as a single module, or interacting modules?
4. Is this even likely to be used by anyone else?

I'm sure i'll think of more questions soon.

FYI, the type of collection in question is a plant collection, specifically a carnivorous plant grow list (i'm webmaster for http://NECPS.org ). It would need to have multiple users, use a hierarchical arrangement of collection item types (ie genus/species/(mother x father parent)/etc), have special users able to modify the plant catalog lists, have a facility for making journal entries attached to a specific plant, a trade listing that is searchable, and a facility for proposing and making trades from the lists of different users. Among other things. As i said, the logic and data (although 2/3 coherent in my head -- at least at one point) is about 1/3 implemented, but the interface is lagging because it's so meticulous to do each editing form manually. The stuff that is currently accessible to the user can be seen by clicking on trade in the menu of the above link. I imagine this would be pretty adaptable to most types of collections with a little careful generalization in implementation.

So, as a new Drupal user who really needs to be able to display images in blog posts and stories, where do things stand with that option at this point? What exactly are my options? Is there an easy way yet for non-techie users (who will use my site) to add images to their content? I'm using 4.6. I'm having trouble tracking all the possibilities and threads on this topic. Thanks much.