How do the Dynetics-led team's ALPACA lander's "drop tanks" rendezvous and jettison work in terms of trajectories?

Ars Technica's NASA awards lunar lander contracts to Blue Origin, Dynetics—and Starship says:

NASA announced Thursday that it has awarded three contracts to begin initial development of lunar landing systems that will take astronauts down to the surface of the Moon in less than five years.

...The awards, which cover a period of 10 months, were given to the following teams:

• $579 million to the Blue Origin-led "National Team." Blue Origin will serve as the prime contractor, building the Blue Moon lunar lander as the "descent element" of the system, along with program management, systems engineering, and safety and mission assurance. Lockheed Martin will develop a reusable "ascent element" and lead crewed flight operations. Northrop Grumman will build the "transfer element," and Draper will lead descent guidance and provide flight avionics. It will launch on a New Glenn rocket. •$253 million to a Dynetics-led team. The company's proposal for a lunar lander is non-traditional and includes Sierra Nevada Corporation as a major partner. The ALPACA lander has a pair of drop tanks that are launched separately, which allow the main lander to be reused. These tanks are depleted and then jettisoned during descent. ALPACA could be launched on United Launch Alliance's Vulcan rocket.

• \$135 million to SpaceX. The company bid its Super Heavy rocket and Starship to carry humans to the Moon. The benefit of Starship is that if the vehicle is successful, it would offer NASA a low-cost, reusable solution for its needs.

Question(s):

1. Since the ALPACA lander's "drop tanks" are launched separately I'm assuming that they are "picked up" somewhere; how and where does that rendezvous happen?
2. When the "drop tanks" are jettisoned during descent, do they drop to the surface? Does this mean that there will be an approach path to a given site that will be considered dangerous and off-limits for rovers or static installations because of a rain of falling debris? Are they basically relatively high velocity impactors that must always be carefully aimed away from all existing assets on the Moon's surface?
• Recent tweet by Bruno indicates that Centaur V long duration capability will be used, likely for direct injection into lunar orbit. twitter.com/torybruno/status/1255957202323505154 However it might be the case that Dynetics are leaning more towards using a SLS Block 1B to launch the entire lander at once, given that the render they released used it. youtube.com/watch?v=GFBeVQ3STZ0 May 1 '20 at 2:49
• Upon further inspection of the video, at 0:55 you can see the fuel tanks hit the surface on the left side of the screen. They're going fairly slow and aren't that far away. youtu.be/GFBeVQ3STZ0?t=55 May 3 '20 at 10:09