Hello Mudmux,
Welcome to the forum :-D
Well... you could start with the Stereo Line Out module only and then see if you miss the Headphones, if yes you buy that one too :-) You don't have to buy everything in one go. It's advised to take it slowly and buy only a few modules in one go, get experience with those and the (re-) adjust your opinion on those you still want to buy, and then buy again a few, etcetera.
Sorry, can't help you with the ALM hpo, don't know that module, perhaps someone else who got it can help you with that one.
Good luck with modular synths and kind regards, Garfield Modular.
For review reports of Eurorack modules, please refer to https://garfieldmodular.net/ for PDF formatted downloads