IKEA sink base cabinet, panel, drawer front metal strips

Hello everyone, I hope someone can help me so that I don't have to go to Ikea again.
I bought parts of my new kitchen back in Dec. 2014, which I can only assemble now.
Question about sink base cabinet and panel:
I have assembled the base cabinet for the stove and the sink, which according to the instructions are basically identical. On the back of the bottom panel there is an approx. 43x6cm cutout covered with a "metal grid" for ventilation. The panel to be mounted at the top front of the cabinet for the sink has 2 drill holes on the left and right in the instructions, each of which is supposed to be used to attach the enclosed brackets. However, my Ringhult panel (20cm high) has 4 drill holes each. In the post here by Neurotroph (21.09.2014) an IKEA expert pointed to an assembly instruction for the sink in which the illustration of the panel attachment shows 4 drill holes on the panel like mine, but the base cabinet looks somewhat different from mine. In that one, both the bottom panel at the back has this cutout, and the back wall at the bottom (a larger one). My base cabinet looks different because it has no cutout on the back wall, but the instructions about the panel are correct. In every instruction something is right and something else is not. What is the cause of this?
Question about drawer front:
For my drawer Maximera (waste separation system) I got a 40cm and a 20cm wide Ringhult part for the front paneling. Among the associated parts there are two white 20cm long "metal strips" which are supposed to be screwed onto the two front panel parts for connection; the drill holes in the metal parts do not match those on the panels, and therefore according to the instructions are supposed to be attached with chipboard screws and pre-drilling. The metal parts seemed too short to me, the screws too thin to withstand the drawer being pulled out in the long run. Also, in the middle of the metal parts there is a white 10cm deep spacer that is visibly unattractive from the front between the gray front parts. At Ikea they could not explain why these metal strips were included (they are also shown in the assembly instructions), because you would have to buy (other) metal strips separately. I bought these (Utrusta, 602.635.88), they are 55.5cm long and much more stable. However, in the instructions there are only options to connect two panels of equal width (each 30cm?), three of equal width (each 20cm?), or six of equal width (each 10cm?) with them. The parts with 20 and 40cm width that I was given back then are not listed, and the drill holes on the panels and the metal connection parts do not seem to quite match each other. What are the correct metal strips now? The short white ones (130511) that came with it, or the new long metal-colored Utrusta parts? Strangely, the front panels in the instructions also each have a recess at the top, mine do not have this.
Thank you for your patience in reading this far.

Hello,

1) Instructions drawn only for one width or small product changes over time.
2) 130511 was initially supplied with the 45 cm deep drawer, just like it was with Faktum/RATIONELL. This was changed and now there is only the UTRUSTA connecting rail.
The illustration with two fronts shows two 40 cm high fronts. 40 cm and 20 cm must be mounted in the same way.

Thank you IKEA expert, yes, that was possible, however I had feared that this front might possibly "bend away" upwards after frequent opening even with the long and massive connecting strip. Unfortunately, this is already the case after the (correct) installation. Let's see if something can be adjusted or improved via the running rails. I seem to have bad luck with IKEA, because during my last visit I was sold a "small" drawer between the waste separation system and the sink - No.: 302.046.37 - which protrudes forward in thickness beyond the white front part received with it, so that I can no longer close the lower drawer (40 20 cm front). I fear that this cannot be adjusted via the running rails.

You cannot adjust anything on the [Korpusschienen]. You adjust the inclination of the front on the [Relingstangen].

I seem to have bad luck with Ikea, because during my last visit I was sold a "small" drawer number: 302.046.37 placed between the waste sorting system and the sink - which protrudes forward beyond the thickness of the accompanying white front panel, so that I can no longer close the lower drawer (40 x 20 cm front). I fear that this cannot be adjusted via the runners.

Should that be an inner drawer? If you cannot push it in far enough, you have probably used the wrong holes for mounting the runners. This is shown quite clearly in the instructions (2nd hole for inner drawer). Regards, IKEA friend