Choosing old programs from backup and do they work with the new operative?

Documents are not 32 or 64-bit dependent, so yes, the very latest Pages (v10.3.5 as of this post) can open Pages '05 thru Pages '09 documents, and later versions. The caveat is that if the older documents use features from their older applications that are not supported in the new Pages, then it may not open those documents, or can present the content differently.

No 32-bit applications are supported in macOS Catalina (10.15.7), or in Big Sur (11.0.1). That means that Apple's iWorks '09 suite, iPhoto v9, iMovie 9.0.9, Microsoft Office 2008/2011, any non-subscription Adobe software (e.g. CS2 - CS6) and probably most of your ten-year old software won't be compatible with the preceding operating systems.

Apple introduced Photos with macOS 10.10.3, and Pages, Numbers, and Keynote are not their counterparts found in the iWork '09 Suite, but can open most of the documents created by iWork '09, except where certain features were not implemented in the later applications. Microsoft now supports Microsoft 365, a subscription plan, or the single-purchase Office 2019 for Mac. There are replacement applications for those that do not want an Adobe subscription.

There is a free application (Go64) that can show you what is 32-bit , and what is 64-bit compiled applications. In many cases, you may be faced with current versions of older software that may or may not cost to upgrade, or old software that is no longer produced.

I would forget bringing your old apps across. Make a list of them and any purchase codes, then fetch up to date copies of the apps from the developer websites.

Perhaps Roaring Apps can help too. https://roaringapps.com/apps

make sure you have good Time Machine backup for your own data

Take a look at Scrivener or Storyist in the Mac App Store. Both have free trials from their website. Many novels have been written in these applications.