If this card is in my hand, and I have exactly 2 Yellow Tamers. Can I play this card with [BT6-112 BeelStarmon]'s [On Play] effect?
Yes, you can. Hoewver, it cannot be taken from your trash by BeeleStarmon's [On Play] effect even if you have 2 Tamers.
If I use this card while I have 8 or more of my own yellow tamers and a [EX2-003 Viximon] in my Digimon's digivolution cards, will that card's inherited effect be triggered?
No, in that case, since the usage cost of [BT2-099 Glorious Burst] has been changed to 1, it is not considered that an option card with a usage cost of 2 or more was used, so it will not be demonstrated.