Learn Dutch: Ik leer altijd Nederlands.

This is because of a very important Dutch spelling rule! The infinitive (the full verb) is leren. When you drop the -en to find the stem, you get ler. Because ler ends in a consonant, a single e would sound short. To keep the long vowel sound from the original verb, we have to double the vowel to make it leer.

Is leer the form I should use for all subjects?

No, leer is the basic stem (often called the ik-form). It is used exactly like this for ik (I). For other singular subjects like jij (you) or hij/zij (he/she), you usually add a -t to the stem, making it leert.

Why is the word order Ik leer altijd and not Ik altijd leer like in English?

In a standard Dutch sentence, the verb almost always takes the second position. This means the verb leer must come right after the subject ik. The adverb altijd (always) follows the verb, unlike in English where "always" goes before the verb.

Do we always capitalize languages in Dutch, like Nederlands?

Yes! Just like in English, words for languages, countries, and nationalities always start with a capital letter in Dutch.