You'll have to buy Snow Leopard so you can access the App Store. The only way to get Lion is through the App Store (the software app or the brick & mortar place, if one is nearby). Or, of course, you can simply buy a new Mac, perhaps a mini?
Depending on how old your Mac is, I see no real need to upgrade, frankly. Of course, the longer you wait, the more likely the internal drive is to crash/die. But, you are making backups of everything, several times a day, right? On at least two external drives...
Not sure what you're using Apple Works for, but it definitely is not going to run on Lion, nothing that requires Rosetta will work on Lion. You can easily check your apps by using System Info and selecting "Software"->"Applications" Anything that shows "PPC" in the 'Kind' column will not work on Lion.
But you should seriously update any app that you depend on, anyway, in my humble opinion. Keynote (as well as Pages and Numbers) are available for $20 each (less than they were as a bundle). But when you update, you don't need to completely delete the old version at the same time. If you have a bootable external drive (which I hope you do, anyway) you could install the new version(s) there and exercise them with the files/documents you have. There will certainly be new features that yo'll need to learn and you should see some ways to increase your efficiency and develop a better work flow. Once you determine that the new version is stable, swap the two versions. Keeping the old one around, on the external drive, until absolutely sure you don't need it any longer.
Seriously, if I were running a business with my computers, I would have at least three external drives, two for backups (one of which is off-site while using the other) and the last one as a bootable backup via SuperDuper/CarbonCopyCloner. Their sizes would be at least twice the size of the internal drive(s). Since this hardware is for your business/livelihood, you should be getting some tax relief thus helping pay for them.
Many others here, should be able to discuss all those Adobe apps. My main concern is that you wean yourself off AppleWorks ASAP. It is only prolonging the agony you'll feel if you continue to depend on it. Bite the bullet, preferably not a steel jacketed one! Ouch!