Word Usage – Should It Be ‘A List of Item’ or ‘A List of Items’?

Risking to express a controversial opinion, I would say that technical documentation has slightly different priorities than normal texts. Being in I.T., I read and write tons of technical papers, and I always prefer readability and text size versus formal grammar.

Think for a moment, your reader is often a non-native speaker as well, but, most certainly, they are a busy person. Overuse of large grammar constructs may just increase the size of your writing, without adding any value.

No, I don't say your document should be ungrammatical. Instead, it must be based on keywords, the shorter the better (unlike my answer :-)
Let's review individual phrases (I took those from your original edit):

• Description of the Project vs. Project Description — are you really sure that project is strongly necessary? If you leave just Description, wouldn't it make your documentation more succinct? I think, it would; There's also special terms, purpose and abstract to denote sections containing verbose description of a project and its rationale;
• Justification of the project — I wouldn't use justification at all. It has several meanings, and you may confuse your reader. Alternatively, it may be review, analysis, or clarification, depending on the context;
• Definition of the scope of the project — there's a term, Scope of Work;
• Bounding of the projects — use Special Requirements or Dependencies instead;
• Benefits of this proposal — just a keyword, benefits, seems to be sufficient (indeed, if not of this proposal, of what then?);
• Competitive Advantages — it's a term by itself, stick to it;
• Deliverables of the project — Deliverables and Artifacts are standard terms;
• Preliminary schedule of this project — just schedule. Everyone understands that it your schedule is proposed, therefore it is subject for change, and, because of that, is preliminary;

Summarizing:

• Use keywords, separate the wheat from the chaff;
• Use widely approved terminology, don't reinvent the wheel;

• I will arrive there at about 8 o'clock or a little later (i.e. at 8:05 or 8:15...)
• I have read about 10 books on Chinese history or a few more (i.e. maybe 11 or 12, I'm not sure).
• She looks 40 years old or a little older (i.e. maybe 42-43).

Both 'or so' and '-odd' can mean either a little more or a little less. If you want the number X to be understood to be the smallest approximate number, you might use "at least X" or "X or more" or "more than X".

• I won't make it there before 8 o'clock. I will probably be 10 or so minutes late.

If you are certain you won't arrive before 8 o'clock, you should say so directly. Otherwise, we would just say "around 8 o'clock, but I might be a little late." with the understanding that if we are lucky and don't have to stop at too many traffic lights, we might show up at 7:55.

• I have read more than 10 books on Chinese history.

If the number were much higher than 10, we would expect you to say "I have read more than 40 books." or "I have read about 100 books on Chinese history."

• She looks at least 40 years old.

Similar to the second example, if you thought she could be a lot older than 40, you might say "She looks around 50 years old." meaning maybe 48 or maybe 52.

I personally find the -odd suffix difficult to use. It always seems better to me to say "about 5 things" instead of "5-odd things". Usually I don't use it with a specific number. I might say for example,

"That sandwich has been in the fridge for a week and some-odd days - throw it away!"

That would mean it has been at least a week and a few days more. If I hear other folks use it in conversation, it doesn't strange to me at all, so don't think I'm telling you not to use the -odd suffix. I would just take someone else's advice on how to use it naturally in your examples.