new iPhone user - 5 missing features?

After a long time with Windows Mobile devices, I finally bit the bullet and switched to a factory unlocked iPhone 3Gs.
I am very pleased so far with the additional functionality and overall speedy experience.

There are a few things, I assumed will work more flawlessly than with my Samsung i780 before deciding for the iPhone, but they don't - some of them seem to be locked completely.

1. data storage and sync

I used to have my company data archive with me on my mobile as a synced ever ready backup. When on a trip without a laptop, I could open an excel sheet, study a technical drawing or could provide a CAD file to a supplier on an instant.
How do I do that on the iPhone?

2. mail folders and work with pop3 accounts

Some mail accounts are pop3.
When I used them, to answer important mails, I could easily sync these sent mails to mail.app, to have my sent mails in the archive.
How do I do that on the iPhone?

3. GPS - sort of

I use Mapking 2007 on my Samsung i780 with maps, that cover Asia including very detailed maps of important cities like Hong Kong, Guangzhou, Shanghai, …
With this software I can easily navigate in China. Google maps is of no real help here. The compass in combination with a map though works better for navigation by foot in a foreign city than the navigation software.
Is there an offline navigation software, that works with the iPhone even, when there is no telephone signal or WiFi, that is in English and allows for detailed search, find and navigate?

4. Safari Topsites

I am an Topsites addict and do my main web surfing from the Topsites menu. Is there a possibility for Safari on the iPhone, to implement that function?

5. mobile as a modem for laptop

I used my Samsung i780 regularly, to connect my MBP to the internet for receiving mails.
How do I do that on the iPhone? There should be a function for tethering in the preferences, which seems to not exist in my phone.