Upgrading from SMF 2.0.11 to SMF 2.0.15

[MegasXLR]

I'm having thoughts of updating from 2.0.11 to 2.0.15 as well but have many questions.
Firstly, is there a way to upgrade my website without losing any information or if I want to upgrade everything will get reset to default?
Secondly, would all my currently installed mods work fine after the upgrade? I have installed some that say they are not compatible with 2.0.11 but still work fine when installed after I change the SMF version for the installer.
And finally, would I be able to use PHP 7.1 with the 2.0.15 build and would my forum topics or something else bug because of that?

I'm sorry if these questions are dumb but I'm new to web stuff and am scared to do whatever as I don't want to ruin my site. But 2.0.11 is getting old now so thought I'd ask.
Any help is appreciated

[Kindred]

Your data is in the database. The database is not modified at all.
(However, ALWAYS ALWAYS ALWAYS take a backup of your files and your database BEFORE doing ANY modification, including an upgrade)

yes. Do the package manager patches.   Go from 2.0.11 to 2.0.12 to 2.0.13 to 2.0.14 to 2.0.15
(Incidentally, any mod for any 2.0.x version will generally work for most other 2.0.x versions)

If you use the full upgrade archive file, you will have to reinstall your mods - which is why we have the patches.

You can use php 7.0 or 7.1 with 2.0.15
However, those versions of php will NOT work for SMF versions before 2.0.14
However, again, you must have at least php 5.4 in order to upgrade to 2.0.14 or 2.0.15.

so, suggestion is:   use php 5.6. Upgrade using the patches. Then update php to 7.1

[MegasXLR]

Your data is in the database. The database is not modified at all.
(However, ALWAYS ALWAYS ALWAYS take a backup of your files and your database BEFORE doing ANY modification, including an upgrade)

yes. Do the package manager patches.   Go from 2.0.11 to 2.0.12 to 2.0.13 to 2.0.14 to 2.0.15
(Incidentally, any mod for any 2.0.x version will generally work for most other 2.0.x versions)

If you use the full upgrade archive file, you will have to reinstall your mods - which is why we have the patches.

You can use php 7.0 or 7.1 with 2.0.15
However, those versions of php will NOT work for SMF versions before 2.0.14
However, again, you must have at least php 5.4 in order to upgrade to 2.0.14 or 2.0.15.

so, suggestion is:   use php 5.6. Upgrade using the patches. Then update php to 7.1

Just upgraded to 2.0.14 with no problem. Thanks for clearing things out about the patches and PHP versions. 2.0.15 gives one error with my theme (SimpleGTA) but I will probably backup and try it sometime soon.