I have a 15 month old too. 😍 He is not verbally inclined so I'm completely fascinated reading about your baby's language interest and ability!! There's plenty of evidence validating that a parent's gut instinct is very accurate in identifying gifted children. Trust yourself!
As far as screens, I'm not okay with passive consumption of media for myself or my kids. no television here. (game console for occasional DVDs and rare Minecraft play for my oldest).
My 15-month-old loves touchscreen games he can manipulate. Daddy is teaching him to play Clash of Clans. 🙄 My guy loved the Smart Baby sorting games for iPad, but he has moved on to physical puzzles, trying to put lids on containers and extend his bath by putting the drain plug back in. He enjoys Little Write iPad app, although he can't yet trace a curved line on his own and loses interest. When he is sleepy he enjoys Starfall ABC's app. We cuddle up together, he picks the letters (totally random) and I sing/talk along. Sharing the names of the apps because I had a hard time finding anything decent.
Screen time is limited to rough bedtimes when he would rather fight sleep and scream. Screen babysitting if I'm stuck running errands and he's fussy. Or any time I have patience to deal with his tantrum when screen time ends. 😂. so not very often. Mostly because he gets bored with the apps and starts getting into the wallet section of my tablet case!!