Really, you don't need a whole lot. Not that many laptops offer a true "docking station" these days, unless you get a high-end business model. Since almost everything has gone to USB, what used to be a "docking station" with a true "[PCI] bus interface" to the motherboard chipset has pretty much given way to so-called "docking stations" that are mostly USB hubs, although some of them do have the "legacy ports" that are no longer present in laptops. This includes PS/2 mouse and keyboard ports, serial and parallel ports, although the manner in which these are implemented (especially serial and parallel ports) is such that they won't work with all software and devices that might use them.
Another concern here is that some devices --- and I mean USB devices --- won't work with USB ports on USB hubs; they require connection directly to a "root hub" on the motherboard or directly on a PCI expansion bus. I know that many USB printers (especially HP) fall into this category, but so do some other devices. Also, while they may work on a hub, things like external hard drives that are really bandwidth sensitive may be seriously degraded operating through an external hub rather than being connected directly to a motherboard USB port. The problem is that many laptops only have 2 or 3 motherboard USB ports, and if you have devices that don't like connections via a USB hub, you can run out of motherboard USB ports rather quickly.
Beyond that, the matter of whether or not a laptop will meet your needs depends on what you needs are, and your preferences. Most desktops today have 19" screens with 1280x1024 resolution (sometimes higher, sometimes "widescreen"), while most laptops are now 14" to 17" "widescreen" models with lower resolutions. So the screen and the keyboard are really two very major considerations for anyone moving from a desktop to a laptop as their primary (non-traveling) computer. Two other major concerns are the video system and the hard drive. Laptop video systems are never, not even close to the equal of what you CAN get (for a lot of money) in a desktop, but they are entirely adequate for most non-gaming and non-CAD applications. And laptop hard drives are both smaller and slower (a lot smaller and a lot smaller) than desktop hard drives. For example, a 160GB 5400rpm laptop hard drive is a "high end" laptop drive, but on a desktop there are 500GB 7200 rpm drives available that will cost less than that laptop drive (and their seek speed and performance is a lot faster as well). So if size and speed (or the ability to have more than a single internal drive) matter, it's a strike against moving to a laptop as your only computer. But, again, the products available on laptops are still entirely adequate for most users.
If these limitations are not in conflict with your needs, then a laptop may well suit all of your needs. As far as what accessories to get, you will need a good case for the laptop and the travel accessories. I'd also get a 2nd AC power supply for the laptop, and an "auto/air" power supply for use in a car and/or airplane. I'd get a wireless optical mouse made for laptops, one that stores it's "receiver" in the mouse itself (logitech and Microsoft both make them). I'd also get a pair of Ethernet cables (straight through and "crossover"), and a travel USB hub with a power supply (get one that has a switching power supply so that it's small and lightweight while still supplying at least 2 amps). If the laptop doesn't have a flash memory card reader, a USB reader that will read all formats is small and inexpensive. And that probably covers most of the things that you will need.
If you are going to be traveling with the laptop, give some thought to data loss and security, which are more important considerations than on a fixed desktop. You need to be FAR more aggressive about backups when you have only one computer, a laptop, that you travel with. Consider that if it's lost, stolen or damaged you don't have a computer to fall back on. And consider the consequences if it's stolen ... you will probably have credit card numbers, passwords, userIDs, social security numbers, date of birth, tax returns and other personal data on the laptop. From an identity theft perspective, the risk in case of loss is substantial. Also, laptop drives (both hard drives and optical drives) are not as reliable as their desktop counterparts. Two things to consider in this regard are an extended warranty (in particular one that includes accidental damage coverage) and an insurance policy that explicitly covers the laptop (your homeowners policy might do this, perhaps with a low-cost rider, but check with your insurance agent).
[Personally, although it's more expensive, I still like having a desktop "primary" computer and a laptop as well, as a 2nd computer, for traveling.]
Hope that this helps,