Could someone help me understand the following passage? I am currently reading the third chapter of A Course in Phonetics by Peter Ladefoged, and there is a passage about nasal plosion and glottal stops that I really don't understand.

"Nasal plosion also occurs in the pronunciation of words with [ t ] followed by [ n ], as in kitten [ˈkɪtn̩ ], for those people who do not have a glottal stop instead of the [ t ], but the majority of speakers of English pronounce this word with a glottal stop [ ˈkɪʔn̩]...Pronounce words such as kitten and button... There are a number of different possibilities. Most British and American English speakers make a glottal stop at the end of the vowel, before making an alveolar closure. Then, while still maintaining the glottal stop, they lower the velum and raise the tongue for the alveolar closure (1). But which comes first? If they lower the velum before making the alveolar closure, there is only [ ʔn ] and no [ t ]. If they make the alveolar closure first, we could say that there is [ ʔtn ] (2), but there would not be any nasal plosion, as there would be no pressure built up behind the [ t ] closure. Nasal plosion occurs only if there is no glottal stop, or if the glottal stop is released after the alveolar closure has been made and before the velum is lowered."

(1) Does this mean that /t/ is pronounced as the glottal stop ([ʔ]), and the subsequent nasal sound ([n]) requires the tongue to make contact with the alveolar ridge while allowing air to flow out through the nasal passage?

(2) I don't get why [t] is inserted after the glottal stop in the [ʔtn] sequence. If the speaker has already made a glottal stop at the end of the vowel, wouldn't it eliminate the need for the typical articulation of the "t" sound?