Is the choice of plugins correct for building a large project on WP?

Question

WordPress

Hello. We are trying to understand what CMS to take as the basis of the project. We study 3 systems in parallel: MODX, WP, Joomla.
The task is to get away from custom solutions as much as possible, in favor of ready-made assemblies, plugins, modules, including paid ones.
During the analysis, WP managed to assemble the following plugins to solve our problems:
Site regionality (site.ru/spb or spb.site.ru)
WP Multisite
Multilingual interface
As I understand it, it is also implemented through WP Multisite
Multilingual articles
Through Polylang
Custom fields
Advanced Custom Fields Pro
Unsolved problems:
1) Is it possible to set the logic of behavior through custom fields? For example, there is an ID field, a variable is entered into it in the admin panel, based on it, an API request is executed and we get the data that the API returned when entering the page? The logic may be different, depending on the categories/categories of articles.
2) Is there a separation of user rights? For example, copywriters have access only to their articles, editors - everything, administrators - system settings.
3) Integration of additional solutions - conditionally, if we want to build our own online store based on WP, and we know for sure that not a single ready-made solution will suit it, how costly in terms of money and time will such an implementation be? Pages will have their own logic, their own fields in the database, which are needed for this task.
4) Organization of e-mail / sms mailings with different templates within the system users
5) Flexibility of work within one URL
Conventionally, for the first half of the year there will be articles on the URL, then the articles move to another URL address, while the URLs of the articles themselves do not change. And in place of the already "old" URL, we expand the custom directory. How easy is this to implement within WP?
It seems to be everything .. Thanks to everyone who can master at least a part :)

Answer 1

Multilingual interface
As I understand it, it is also implemented through WP Multisite
This is implemented by the WP core itself.

Site regionality (site.ru/spb or spb.site.ru)
WP Multisite
Multilingual articles
Via Polylang

These are two different approaches to solve the same problem. WP Multilingual uses the WP Multisite mechanism - each language version is a separate web site. Translations, in fact, are separate posts in these separate sites. They link to each other with the help of this plugin. Polylang is a plugin for multilingualism within a single site. Pick one. Pluses of Multisite - completely independent local versions, flexibility in work. Cons - duplication of media files (although there is a workaround hack). In your case, Multisite is likely to be the best option.

Advanced Custom Fields
5 Pro

Great choice, we use it ourselves, we recommend it to everyone.
Yes, ACF Pro has conditional logic. On the output in the topic, in any case, you will have to code a little, regardless of the solution.
Yes, that's exactly how it works, it's a core feature of WP. There are plug-ins for fine-grained management of roles and rights, the creation of new ones, we have been using User Role Editor for many years .
Just as costly and hemorrhagic as any other solution. WP is a bunch of PHP files, among which is a bunch of low-level APIs for working with the file system, HTTP, database, etc. (essentially a framework). In December, the JSON REST API will also appear in version 4.4 . All in all, WP, thanks to these APIs and hooks, is a very flexible thing that can be crossed with anything. As for specifically commerce - WooCommerce, Easy Digital Downloads. I don’t know yet the tasks for which WooCommerce would not be suitable, which in its flexibility is in no way inferior to WP itself. Not so long ago, WooCommerce was acquired by Automattic, which (with some caveats) is behind the entire WP project. So it will only get better with time. Well, the numbers speak for themselves - 30% of all online stores on the Internet are powered by WooCommerce.
No problem. There are a lot of plugins, both for working with newsletters natively (within WP), and through integration with third-party services, such as MailChimp. Also, it makes sense to mention that in WP it is easy to connect and configure a third-party service for transactional emails, such as Mandrill.

5) Flexibility of work within one URL
Conventionally, the first half of the year there will be articles on the URL, then the articles move to another URL address, while the URLs of the articles themselves do not change. And in place of the already "old" URL, we expand the custom directory. How easy is this to implement within WP?

Realizable. WP has its own system of internal redirects, there are plugins.
If there are other questions - contact. I have experience in developing large custom projects (including SaaS-platforms based on WP), for 10 years of work on plugins and custom code we have figured it out well :)