Opinions on this estimate for an AC Pro-brand and Lennox Unit?

I'm helping a relative review estimates for a new HVAC system. They need to replace their 30-year old system (both AC and furnace.) Don't worry, I'm convincing my relative to get other estimates, but this one had a few curiosities I was hoping the pros here could sort out. It's from an authorized Lennox dealer who was referred via the Costco program (currently: earn 15% Costco cashback on Lennox installations.)

Profile of my relative's house...

• Single-story
• 1900+ sq feet
• San Diego County (inland)
• Although San Diego is generally a mild climate, they have a large wall of windows over most of the back side of the house which get a lot of direct sunlight, so it can get quite hot when temps rise. And, in winter, in their part of San Diego, temps can drop into the high 30s in winter, so they make good use of the heat, too.

This is the model condensing unit they are recommending:

• Brand/Manufacturer: AC Pro
• Model: X-Series Condenser Air Conditioning
• BTU: 42,000-60,000
• Model number: AULD60W2/A-D(U)
• SEER: "Up to 20", according to their brochure
• Website: As a new user I'm not allowed to post a link but you can find this unit on the AC Pro website

This is the model furnace they are recommending:

• Manufacturer: Lennox
• Model: Low NOx Elite Series, Upflow/Horizontal Gas Furnace, 80% AFUE, 88,000 Btuh, Power Saver Constant Torque, 2 Stage, 3-4 Ton,
• Model #: EL280UH090XE48B
• BTU: 42,000-60,000
• Website: I can't post a link as a new user, but you can find this unit on Lennox Pros dot com.

Questions for you...

1. The dealer's recommending a condensing unit made by AC Pro -- model #: AULD60W2/A-D(U). They said it's actually manufactured by Lennox, though this has been difficult to verify when contacting both Lennox and AC Pro directly. Regardless. Any experience with or things to watch out for with AC Pro brand or this particular model?
2. Any thoughts on the recommended furnace?
3. Anything to be concerned about regarding them saying they will "use existing" refrigerant lines? I have no idea if this matters, but the current HVAC system was installed in the early 90s.
4. Any other particular questions you'd recommend we ask the HVAC specialist?

Here's the estimate in case it's helpful (I know you can't provide any feedback on pricing):



Thank you so much for reading and responding -- appreciate the HVAC experts who are willing to share some of their knowledge and expertise with total novices like us! (I posted this on Reddit, too, so apologies if you see it twice!)

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